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lEjmxmtxmnl Paiirtiologti jTOfluograyl^g 

No. 18 

THE STANFORD REVISION AND EXTENSION 

OF THE BINET-SIMON SCALE FOR 

MEASURING INTELLIGENCE 



Bt 

Lewis M. Terman, Grace Lyman, George Ordahl, 
Louise Ellison Ordahl, Neva Galbreath 

AND WiLFORD TaLBERT 

Absistbd bt 

Herbert E. Knollin, J. H. Williams, H. G. Childs, Helen 

Trost, Richard Zeidler, Charles Waddle 

AND Irene Cuneo 



BALTIMORE 

WARWICK & YORK, Inc. 
1917 



LZB//3/ 
■Ts- 



Copyright. 1917, 

By 

Warwick & York, Inc. 



M -4 1918 

©CI,A481957 

.1 



/VvO 



Dedicated 

by 
Lewis M. Terman 

to 

Those whose loyal cooperation 

made the study possible 



EDITOR'S PREFACE 

The labors of Professor Terman and his co-workers 
at Stanford University in the critical examination and 
improvement of the Binet-Simon Scale for Measuring 
Intelligence are so well and so favorably known by 
psychologists and by the many users of the method 
that no words of editorial introduction are needed to 
call attention to the importance of the present mono- 
graph. 

The results of these labors are embodied in the Stan- 
ford Revision of the Binet-Simon Scale. A general 
guide for the application of this Revision has been' 
published elsewhere. In the present monograph, how- 
ever, the reader is taken '' behind the scenes/' is shown 
the precise methods by which the Revision was made, 
the actual data on which it was based. There is intro- 
duced also an instructive discussion of a number of 
very salient questions: What is the nature of intelli- 
gence? How is intelligence distributed? What sex 
differences exist in intelligence? What is the relation 
between intelligence and social status? Between 
intelligence and school success? Is the intelligence 
quotient a vaUd measure? How shall the validity of 
any single test in an intelligence scale be determined? 
What principles should govern the assembling of 
tests into a system, or scale? These questions have 
more than a merely technical interest: they bear in 
many ways upon practical problems of school instruc- 
tion and administration. The monograph should do 
much to stimulate and to clarify thinking, both in 
psychological and in pedagogical circles. 

G. M. W. 



PREFACE 

The present monograph summarizes the data on 
which the Stanford revision and extension of the Binet 
scale rests and gives an analysis of the results secured 
by the application of the revised scale with nearly 
1000 unselected school children. 

The complete guide for giving and scoring the tests 
and for the interpretation of results is pubUshed 
separately: The Measurement of Intelligence (Houghton 
Mifflin Co., 1916). This and the present monograph 
are in a sense companion volumes, and it is especially 
hoped that all who use the guide will also make them- 
selves familiar with source material herein offered. 

The responsibility of each of the various collabora- 
tors is related in Chapter I. Terman is responsible 
for the assembling of the source material, the arrange- 
ment of the trial series, the scoring of all the records, 
the elaboration of the revision from the results, the 
formulation of the procedure, the analysis of the data, 
and the preparation of this monograph for the press. 
In all these matters, however, invaluable help was 
rendered by all who collaborated in the work. What- 
ever merit the present revision possesses must be 
credited in no small degree to the loyal and painstaking 
work of those who assisted in the tests. Hearty thanks 
are also due the public-school officers, teachers, prin- 
cipals and superintendents for their always willing 
cooperation in furnishing pupils for the tests and in 
supplying the supplementary information called for. 

Lewis M. Tekman. 

Stanford University, June 12, 1916. 

3 



TABLE OF CONTENTS 

Page 

Chapter I. — Brief Account of the Revision and Its History 7 

Chapter II. — The Distribution of Intelligence 26 

Chapter III. — The Rate of Growth and the VaHdity of the I Q. . . 51 

Chapter IV. — Sex Differences 62 

Chapter V. — The Relation of IntelKgence to Social Status 84 

Chapter VI. — The Relation of InteUigence to School Success 104 

Chapter VII.— The Validity of the Individual Tests 129 

Chapter VIII. — Some Considerations Relating to the Formation 

of an InteUigence Scale 146 

Appendix (1). — Statistics on the individual tests 163 

Appendix (2). — Form used for supplementary information 179 



CHAPTER I 

BRIEF ACCOUNT OF THE STANFORD REVI- 
SION AND ITS HISTORY 

Terman and Childs' tests of 396 children in 1910- 
1911 afforded data for a tentative revision and exten- 
sion of the Binet 1908 scale. The most important 
changes introduced into the test series by that revision 
involved a shifting downward of most of the tests in 
the lower end of the scale, a shifting of several of the 
upper tests in the opposite direction, and the addition 
of the following new tests: the ^^ball and field" test, 
a graded completion test, and a graded test of vocabu- 
lary and fable interpretation. ^ 

In 1911-1912 the tentative revision was applied to 
310 public school children in Palo Alto, San Jose and 
Los Angeles. Of these, 127 were tested by Miss Helen 
Trost, a senior student at Stanford University, 52 by 
Dr. Charles Waddle, of the State Normal School, Los 
Angeles, and the remainder by Terman. The children 
were selected from each grade by arbitrary rule, accord- 
ing to seating when this had not been determined by 
scholarship, otherwise alphabetically. The schools 
selected were attended chiefly by children of the middle 
classes. The number at each age is given on p. 9. 

For several reasons the results of this study did not 
afford satisfactory data for a further revision of the 
scale. The method of selecting subjects failed to give 
representative children at all the various ages, and too 

^Lems M. Terman and H. G. Childs: A Tentative Revision and 
Extension of the Binet-Simon Measuring Scale of Intelligence. /. oj 
Educ. Psych., Vol. 3, Feb., Mar., Apr. and May, 1912. 

7 



8 STANFORD REVISION OF BINET-SIMON SCALE 

little attention had been given to securing uniformity 
of procedure. Moreover, some of the features of the 
Terman and Childs revision proved impracticable in 
actual use and showed the necessity of a more thorough- 
going revision based on more extensive data. Ac- 
cordingly, a new investigation was undertaken, much 
more extensive than the earlier ones and more care- 
fully planned. 

The work was begun in the autumn of 1913 by Ter- 
man, Lyman and Galbreath. Miss Lyman and Miss 
Galbreath were at the time graduate students in 1];. 
Department of Education at Stanford Universii\\ 
Later, Professor and Mrs. Ordahl, of the University 
of Nevada, and Mr. Wilford Talbert, a former gradu- 
ate student of Stanford University, kindly offered to 
cooperate in the work. During the school year '>! 
1913-1914 approximately 1000 public-school child: e. 
were tested by Miss Lyman, Miss Galbreath, I^tr. 
Talbert, Professor Ordahl and Mrs. Ordahl. The 
following year another Stanford graduate. Miss Irene 
Cuneo, secured further data on the lower tests by applj 
ing the revised scale to the 54 kindergarten child}> '^ 
attending the training department of the California 
State Normal School at San Jose. The accompanying 
table shows the number of children of each age tested 
by each examiner. 

The data secured from these 982 children made 
possible the revision of the scale up to the 14-year 
level, but left the extreme upper part of the scale still 
insecure. Revision of this part was fortunately made 
possible by the following data: 

(1) Tests of 40 high-school students in San Jose and 
Campbell, Cal. Thirty-two of these, tested by Tea- 
man, were members of classes in ^Uife-career stud- " 



I 



THE STANFORD REVISION AND ITS HISTORY 



9 



TABLE I 

Number of Children at Each Age Tested by the Several Examiners 



Examiner 


Place 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


16-17 


Total 


Lyman 

Prof, and 
Mrs. Ordahl 

Galbreath 

Talbert 

Cuneo 


Santa Barbara 
Los Angeles 
Los Gatos, Cal. 

Reno, Nevada 

San Jose and 
Mt. View, Cal. 

Oakland 

Kindergarten 
St. Nor. School 
San Jose 


3 

14 
17 


10 

11 

15 
18 
54 


18 
27 
18 
32 
22 
117 


23 
31 
23 
15 

92 


34 
31 
23 
12 

100 


35 
38 
28 
12 

113 


27 
29 
20 
11 


33 
22 
10 
14 


26 
22 
25 
10 


42 
33 
11 
12 


29 
33 
10 
10 


15 
19 

5 

7 


4 
8 
1 
1 


299 
304 
176 

151 

54 


Total at each age 


87 


79 


83 


98 


82 


46 


14 


982 



and were of junior or senior grade. Their ages ranged 
from 17 to 20, with a median of 18+. The others, 
tested by Mr. Zeidler, were first and second-year 
students from 14 to 16 years of age. The ^^high school 
group," referred to in the statistics, included only the 
32 tested by Terman. 

(2) Tests of 30 business men in Palo Alto and vicin- 
ity? by Knolhn and Zeidler. The men selected had 
had Uttle or no formal education beyond the common 
school but had shown themselves ordinarily successful 
in the various lines of business represented in a smaU 
city. 

(3) Tests of 150 "migrating unemployed" men by 
Mr. Knollin. These were temporary residents at a 
"hobo hotel" conducted at Palo Alto for transient 
pedestrians who were willing to work a few hours 
for a night's lodging and a couple of meals. The 



10 STANFORD REVISION OF BINET-SIMON SCALE 

ages ranged from 18 to 65, but were chiefly between 
25 and 40. Tests of somewhat more than 100 unem- 
ployed men were also made with our trial series by 
Mr. Glenn Johnson, of Reed College, Portland, Ore- 
gon, who kindly loaned us his data for comparative 
purposes. 

(4) Tests of 150 juvenile delinquents in the Whittier 
(Cal.) State School. These tests were made by Dr. 
J. H. Williams, at that time Fellow on the Buckel 
Foundation, Stanford University. The ages of the 
delinquents ranged from 10 to 21, but most were 
between 14 and 19.^ 

Returning now to the tests of 1000 unselected chil- 
dren, this part of the investigation may be described 
as follows: 

1. We first assembled as nearly as possible all the 
results which had been secured for each test of the 
Binet scale by all the workers of all countries, includ- 
ing per cents passing the test at various ages, conditions 
under which the results were secured, method of pro- 
cedure, etc. After a comparative study of these data, 
and in the light of results we had ourselves secured, 
a provisional arrangement of the tests was prepared 
for trial. 



2 As the foregoing studies of delinquents, unemployed, and business 
men are to be published separately by their several authors, it is not 
necessary to enter into them here in detail. Mr. Williams has since 
increased his tests of delinquent boys to nearly 500, and Miss Cuneo 
her tests of kindergarten children to approximately 100. More re- 
cently another Stanford University student has used the revision with 
150 employees, mostly unskilled or semi-skilled. The mental ages 
found are given in Chapter II. 

About a dozen additional studies, involving tests of nearly 1000 
school children and adults, were carried out at Stanford University 
during the school year of 1916-1917. These studies, which will be 
reported in a forthcoming monograph, have sought especially to deter- 
mine the vahdity of the Stanford Revision as a means of diagnosing 
a child's educability. 



THE STANFORD REVISION AND ITS HISTORY 11 

2. A plan was then devised for securing subjects 
who should be as nearly as possible representative of 
the several ages. The method was to select a school 
in a community of average social status, a school at- 
tended by all or practically all the children in the dis- 
trict where it was located. In order to get clear pic- 
tures of age differences, the tests were confined to 
children who were within two months of a birthday. ^ 
To avoid accidental selection, all the children within 
two months of a birthday were tested, in whatever 
grade enrolled (below the high school). Tests of 
foreign-born children, however, were eliminated in 
the treatment of results. 

3. The children's responses were for the most part 
recorded verbatim. This made it possible to re-score 
the records according to any desired standard and thus 
to fit a test more perfectly to the age level assigned 
it. 

4. The tests were made at an average rate of about 
fifty minutes per test. The time was rarely below 40 
minutes, except with the children of four and five 
years. The older children and adults more often 
required from fifty minutes to an hour. In spite of 
the rather long time required for the test we are con- 
vinced that fatigue has been a negligible factor in our 
results. The tasks required of the child are so novel 
that the reserve energies are brought into play and 
attention is kept at high efficiency much longer than 
would be the case with ordinary school work. 

5. As may be inferred from the time required, the 
testing was reasonably thorough. It is possible, how- 
ever, that occasionally a success has been missed by 
not carrying the test high enough, or a failure missed 

' The only exception to this was in the case of 14 five year olds, 
tested by Miss Cuneo. 



12 STANFORD REVISION OF BINET-SIMON SCALE 

by not going back far enough. Errors of this sort 
doubtless about balance in the long run, and so do not 
affect appreciably the distribution of mental ages. 
They do affect, however, the statistical treatment 
of the results for individual tests, and as a rule we 
have given the per cents passing a test only for those 
ages at which all the children were given the test. 

6. Much attention was given to securing uniformity 
of procedure. A half-year was devoted to training 
the examiners and another half-year to the supervi- 
sion of the testing.^ In the further interests of uni- 
formity all the records were scored by one person 
(Terman) . 

In working out a revision of the scale the guiding 
principle was to secure an arrangement of the tests 
and a standard of scoring which would cause the median 
mental age of the children of each age-group to coincide 
with the median chronological age. If the median 
mental age at any point in the scale was too high or 
too low, it was only necessary to change the location 
of certain of the tests, or to change the standard of 
scoring, until an order of arrangement and a standard 
of passing were found which would throw the median 
mental age where it belonged. We had already be- 
come convinced that no satisfactory revision of the 
Binet scale was possible on any theoretical consider- 
ations as to the percent of passes which an individual 
test ought to show in a given year in order to be con- 
sidered standard for that year, although such a plan 
might be feasible with a scale differently founded. 



^ This statement does not apply, however, to Professor and Mrs. 
Ordahl, who had to rely on a 20-page guide, supplemented by a few 
demonstration tests and such further direction as could be given by 
correspondence. Mr. Talbert and Miss Cuneo had also somewhat 
less specific training for the tests than had the others, though both had 
taken a half-year course in clinical psychology. 



THE STANFORD REVISION AND ITS HISTORY 13 

As was to be expected, the first draft of the revision 
did not prove satisfactory. The scale was still too 
hard at some points and too easy at others. Three 
successive revisions were necessary, involving three 
separate scorings of the data and as many tabulations 
of the mental ages, before the desired degree of accur- 
acy was secured. 

As finally left, the scale gives a median intelligence 
quotient closely approximating 100 for our non-se- 
lected children of each age. The revision contains 
six regular tests and from one to three alternative 
tests in each year from 3 to 10, eight tests at year 12, 
six at 14, and six in each of two higher groups which 
are named, in order, ^^ average adult'' and '^superior 
adult." 

The tests in the two highest groups were standardized 
chiefly on the basis of results from 400 adults. The 
extension of the scale in the upper range is such that 
ordinarily intelUgent adults, little educated, test near 
to what is called the '^average adult" level. Adults 
whose intelligence is known from other sources to be 
superior are found to test well up to the '^superior 
adult" level, whether they are well educated or prac- 
tically unschooled. Of 30 uneducated business men, 
15 tested at '^average adult" (15-17), 8 at ^^ superior 
adult" (17-19), 6 at ^'inferior adult" (14-15) and 1 
at 13. Of 32 high-school students who were 16 years 
of age or older, 22 tested at ^'average adult," 5 at 
"superior adult," 5 at "inferior adult." 

The trial arrangement of tests included, in addition 
to those of the Binet 1908 and 1911 series, 31 addi- 
tional tests, as follows: Kuhlmann's test of discrimin- 
ation of forms, two new tests of comprehension (Terman), 
four tests of repeating digits in reversed order (suggested 
by Bobertag), repeating 8 digits, test of ability to tie 
a bow-knot (Terman), two tests of finding similarities 



14 STANFORD KEVISION OF BINET-SIMON SCALE 

(Terman), six vocabulary tests (Terman and Childs), 
two form-board tests (Healy and Fernald), the Healy- 
Fernald code test, two tests of fable interpretation (Ter- 
man and Childs), two ^^ ball and field " tests (Terman and 
Childs), an ^' induction'^ test (Terman), a test of arith- 
metical reasoning (selected from Bonser's series), an 
''ingenuity'' test (Terman), a test of ''comprehension 
of physical relations" (suggested in part by Meumann), 
a test of observation (drawing an apple with pencil 
through it, suggested by an experiment of Professor 
Earl Barnes), and the "problem of enclosed boxes'' 
(Terman). The test of observation proved too un- 
satisfactory to be included in the revision, as was true 
also of one of the Healy-Fernald form boards and 
Binet's "suggestion" and "reversed triangle" tests. 
Counting both regular and alternative tests, the re- 
vision contains 90 tests, as contrasted with 54 in the 
Binet 1911 series. 

As far as possible, the original Binet tests have been 
retained in the form in which they were used by their 
author, although in a number of cases it has seemed 
advisable to introduce alterations either in procedure 
or scoring. In preparing the directions, special at- 
tention has been devoted to the difficulties encountered 
by inexperienced examiners in giving and scoring the 
tests. 5 

While it is not claimed that the revision here offered 
is satisfactory in every respect, the authors believe 
that it possesses a number of distinct advantages over 
other versions of the Binet scale. Among these ad- 
vantages are the following: 

^ An extended guide for the giving and scoring of the individual 
tests and for the interpretation of test results has been pubhshed in a 
separate volume, The Measurement of Intelligence (Houghton Mifflin 
Co., 1916). With the latter is furnished all the necessary material 
for the use of the Stanford Revision. 



THE STANFORD REVISION AND ITS HISTORY 15 

1. Correction of the too-great ease of the original 
scale at its lower end and its too-great difficulty at 
the upper end. This correction should have the im- 
portant result of tending to prevent the overlooking 
of borderline cases of deficiency among young children 
and the overestimation of deficiency among adults of 
somewhat inferior or borderline intelligence.® 

2. The revision not only contains a much larger 
number of tests than any other series, but also brings 
into operation a much greater variety of mental func- 
tions. This is especially true for the upper part of 
the scale. 

3. It is believed that the detailed directions set forth 
in the companion volume for giving and scoring the 
tests should tend materially to promote uniformity of 
procedure. 

The following copy of the forms used in applying 
the tests will serve to indicate their nature. 

YEAR III. (6 tests, 2 months each.) 

1. Points to parts of body. (3 of 4.) 

Nose Eyes Mouth Hair 

2. Names familiar objects. (3 of 5.) 

Key Penny Closed knife Watch Pencil 

3. Pictures, enumeration or better. (At least 3 objects in one picture. 

''TeU me everything you can see in this picture.") 

a. Dutch Home 

b. Canoe 

c. Post Office 

4. Gives sex. (Note form of question.) 

5. Gives last name 

6. Repeats 6-7 syUables. (1 of 3.) 

a. "I have a httle dog." 
h. "The dog runs after the cat." 
c. "In summer the sun is hot." 
Al. Repeats 3 digits. (1 of 3. Order correct. Read 1 per second.) 
6-4-1 3-5-2 8-3-7 



YEAR IV. (6 tests, 2 months each.) 

1. Compares hues. (3 of 3, or 5 of 6.) 1 2 3 

2. Discrimination of forms. (Kuhlmann. 7 of 10.) 

Circle Square Triangle Other errors 

^ For a fuller discussion, see L. M. Terman, Some problems related 
to the detection of border-line cases of mental deficiency, J. of Psycho- 
Asthenics, Sept. and Dec, 1915. 



16 STANFORD REVISION OF BINET-SIMON SCALE 

3. Counts 4 pennies. (No error.) 

4. Copies square. (Pencil. 1 of 3.) 1 2 3 

5. Comprehension, 1st degree. (2 of 3.) "What must you do: 

a. ** When you are sleepy? 

b. "When j^ou are cold? 

c. " WTien you are hungry? " 

6. Repeats 4 digits. (1 of 3. Order correct. Read 1 per second.) 

4-7-3-9 2-8-5-4 7-2-6-1 

Al. Repeats 12-13 syllables. (1 of 3 absolutely correct, or 2 with 1 
error each.) 
a. "The boj^'s name is John. He is a very good boy." 
h. "When the train passes you will hear the whistle blow." 
c. "We are going to have a good time in the country." 

YEAR V. (6 tests, 2 months each.) 

1. Comparison of weights. (2 of 3.) 

3-15 15-3 3-15 

2. Colors. (No error.) 

Red Yellow Blue Green 

3. Aesthetic comparison. (No error.) 

Upper pair Middle Lower 

4. Definitions, use or better. (4 of 6.) 

Chair DoU 

Horse Pencil 

Fork Table 

5. Patience, or divided rectangle. (2 of 3 trials. 1 minute each.) 

1 Time 

2 Time 

3 Time 

6. Three commissions. (No error. Order correct.) 

Puts key on chair Brings box Shuts door 

Al. Age 

YEAR VL (6 tests, 2 months each.) 

1. Right and left. (3 of 3, or 5 of 6.) 

R. hand L. ear R. eye 

2. Mutilated pictures. (3 of 4.) 

Eye Mouth Nose Arms 

3. Coimts 13 pennies. (1 of 2 trials, without error.) 

4. Comprehension, 2d degree. (2 of 3.) "WTiat's the thing to do: 

a. "If it is raining when you start to school? 

b. "If you find that your house is on fire? 

c. "If you are going some place and miss your car?" 

5. Coins. (3 of 4. Present in order given below.) 

Nickel Penny Quarter Dime 

6. Repeats 16-18 syllables. (1 of 3 absolutely correct, or 2 with 1 error 

each.) 
a. "We are having a fine time. We foimd a little mouse in the 

trap." 
6. "Walter had a fine time on his vacation. He went fishing every 

day." 
c. "We will go out for a long walk. Please give me my pretty 

straw hat." 
Al. Morning or afternoon. (Note form of question.) 



THE STANFORD REVISION AND ITS HISTORY 17 

YEAR VII. (6 tests, 2 months each.) 

1. Fingers. (No error.) R L Both . . 

2 P ictures, description or better. (Over half of performance descrip- 

tion. "Tell me what this picture is about?" "What is this 
a picture of?") 

a. Dutch Home 

b. Canoe 

c. Post Office w ' \ jT * * 

3 Repeats 5 digits. (1 of 3. Order correct. Read 1 per second.) 

3il_7_5_9 4-2-8-3-5 9-8-1-7-6 

4. Ties bow knot. (Model shown. 1 mmute. "Single" bow half 

credit.) 
Time Method 

5. Gives differences. (2 of 3.) 

a. Fly and butterfly 

h. Stone and egg 

c. Wood and glass 

6. Copies diamond. (Pen. 2 of 3.) a b .c 

Al. 1. Names days of week. (Order correct. 2 of 3 checks correct.) 

Mon., Tues., Wed., Thurs., Fri., Sat., Sun. 
Al. 2. Repeats 3 digits backwards. (1 of 3. Read 1 per second.) 
2-8-3. 4-2-7 9-5-8 

YEAR VIII. (6 tests, 2 months each.) 

1. Ball and field. (Inferior plan or better.) 

2 Counts 20-0. (40 seconds. 1 error allowed.) Time Errors 

3. Comprehension, 3rd degree. (2 of 3.) "What's the thing for you 

to do: , . , , , 

a. ''When you have broken something which belongs to someone 
else? 

b. "When you are on your way to school and notice that you are 
in danger of being tardy? • • • • • 

c. " If a pla5niiate hits you without meaning to do it? 

4. Gives similarities, two things. (2 of 4. "In what way are wood 

and coal alike?" etc. Any real likeness is plus.) 
o. Wood and coal 

b. Apple and peach 

c. Iron and silver 

d. Ship and automobile 

5. Definitions superior to use. (2 of 4. "Thing" as genus counts 

plus.) 

a. Balloon 

b. Tiger 

c. Football 

d. Soldier ; * ' ', 

6. Vocabulary, 20 words. Score Total Vocab 

Al. 1. Six coins. (No error. Give in order indicated.) 

.05 01 25 10 1.00.... .50 

Al. 2. Dictation. ("See the little boy." Easily legible. Pen, 1 
minute.) 
Time Score by Ayres scale • 



18 STANFORD REVISION OF BINET-SIMON SCALE 

YEAR IX. (6 tests, 2 months each.) 

1. Date. (Allow error of 3 days in c, no error in a, h, or d.) 

a. Day of week. ... 6. month. . . . c. day of m d. year 

2. Weights. (3, 6, 9, 12, 15. Procedure not iUustrated. 2 of 3 

correct.) 

a Method 

b Method 

c Method 

3. Makes change. (2 of 3. No coins, paper, or pencil.) 

10-4 15-12 25-4 

4. Repeats 4 digits backwards. (1 of 3. Read 1 per second.) 

6-5-2-8 4-9-3-7 8-6-2-9 

5. Three words. (2 of 3. Oral. 1 sentence or not over 2 coordinate 

clauses.) 

a. Boy, river, ball 

b. Work, money, men 

c. Desert, rivers, lakes 

6. Rhymes. (3 rhymes for each word. 1 minute for each part. 

Illustrate with hat, rat, cat.) 

a. Day Time 

b. Mill Time 

c. Spring Time 

Al. 1. Months. (15 seconds and 1 error in naming. 2 checks of 3 

correct.) 
Jan., Feb., Mch., Apr., May, June, July, Aug., Sept., Oct., Nov., 
Dec. 
Al. 2. Stamps, gives total value. (2d trial if individual values are 
known.) 

YEAR X. (6 tests, 2 months each.) 

1. Vocabulary, 30 words. Score Total Vocab 

2. Absurdities. (4 of 5. Warn. Spontaneous correction allowed.) 

a. "A man said: 'I know a road from my house to the city which 
is down hill all the way to the city and down hill aU the way 
back'^home. ' " 

b. "An engineer said that the more cars he had on his train the 
faster he could go." 

c. "Yesterday the poUce found the body of a girl cut into 18 
pieces. They beheve that she killed herself." 

d. "There was a railroad accident yesterday, but it was not very 
serious. Only 48 people were killed." 

e. "A bicycle rider, being thrown from his bicycle in an accident, 
struck his head against a stone and was instantly killed. They 
picked him up and carried him to the hospital, and they do not 
think he wiU get well again." 

3. Designs. (1 correct, 1 half correct. Expose 10 seconds.) a. . .b. . . 

4. Reading and report, (8 memories. 35 seconds and 2 mistakes in 

reading.) 

Memories Time for reading Mistakes 

New York. ] September 5th. | — A fire | last night | burned ] three 
houses I near the center | of the city. | It took some time | to put it out. | 



THE STANFORD REVISION AND ITS HISTORY 19 

The loss I was fifty thousand dollars, | and seventeen famihes | lost 
their homes. | In saving | a girl \ who was asleep | in bed, | a fireman | 
was burned | on the hands. 

5. Comprehension, 4th degree. (2 of 3. Question may be repeated.) 

a. "What ought you to say when someone asks your opinion about 
a person you don't know very well? " 

h. "What ought you to do before undertaking (beginning) some- 
thing very important? " 

c. "Why should we judge a person more by his actions than by his 
words? " 

6. 60 words. (Score half-minutes separately. Illustrate with clouds, 

dog, chair, happy.) 1 2 3 4 5 6 

Method 

Al. 1. Repeats 6 digits. (I of 2. Order correct. Read 1 per sec- 
ond.) 

3-7-4-8-5-9 5-2-1-7-4-6 

Al. 2. Repeats 20-22 syllables. (1 of 3 correct, or 2 with 1 error 
each.) 

a. "The apple tree makes a cool pleasant shade on the ground 
where the children are playing." 

h. "It is nearly half-past one o'clock; the house is very quiet and 
the cat has gone to sleep," 

c. "In summer the days are very warm and fine; in winter it 
snows and I am cold." 
Al. 3. Form board. (Healy-Fernald Puzzle A. 3 times in 5 min- 
utes.) 

Time: a b c Method 

YEAR XII. (8 tests, 3 months each.) 

1. Vocabulary, 40 words. Score Total Vocab 

2. Abstract words. (3 of 5.) 

a. Pity 

b. Revenge 

c. Charity 

d. Envy 

e. Justice 

3. Ball and field. (Superior plan.) 

4. Dissected sentences. (2 of 3. 1 minute each.) 

a Time 

b Time 

c Time 

6. Fables. (Score 4, i. e., two correct or the equivalent in half credits.) 

a. Hercules and wagoner 

b. Maid and eggs 

c. Fox and crow 

d. Farmer and stork 

e. MiUer, son and donkey 

6. Repeats 5 digits backwards. (1 of 3. Read 1 per second.) 

3-1-8-7-9 6-9-4-8-2 5-2-9-6-1 

7. Pictures, iQterpretation. (3 of 4. "Explain this picture.") 

a. Dutch Home 

b. Canoe 



20 STANFORD REVISION OF BINET-SIMON SCALE 

c. Post Office 

d. Colonial Home 

8. Gives similarities, three things. (3 of 5. ''In what way are — , — , 

— , alike?" Grade fairly closely.) 

a. Snake, cow, sparrow 

b. Book, teacher, newspaper 

c. Wool, cotton, leather 

d. Knife-blade, penny, piece of wire 

e. Rose, potato, tree 

YEAH XIV. (6 tests, 4 months each.) 

1. Vocabulary, 50 words. Score Total Vocab 

2. Induction test. (Gets rule by 6th folding. Unfold after each 

cutting.) 
1 2 3 4 5 6 

3. President and king. (Power. . . . accession. . . , tenure. ... 2 of 3.) 

a 

b 

c 

4. Problems of fact. . (2 of 3. Query on a and b.) 

a. "A man who was walking in the woods near a city stopped 
suddenly, very much frightened, and then ran to the nearest 
poUceman, saying that he had just seen hanging from the limb 
of a tree a a what? " 

b. "My neighbor has been having queer visitors. First a doctor 
came to his house, then a lawyer, then a minister (preacher or 
priest). What do you think happened there?" 

c. "An Indian who had come to town for the first time in his life 
saw a white man riding along the street. As the white man rode 
by the Indian said — 'The white man is lazy; he walks sitting 
down.' What was the white man riding on that caused the 
Indian to say 'he walks sitting down'?" 

5. Arithmetical reasoning. (1 minute each. 2 of 3.) 

a. If a man's salary is $20 a week and he spends $14 a week, how 
long wiU it take him to save $300? 

6. If 2 pencils cost 5 cents, how many pencils can you buy for 50 

cents? 

c. At 15 cents a yard, how much will 7 feet of cloth cost? 

6. Clock. (2 of 3. Error must not exceed 3 or 4 minutes.) 

6 :22 Time required 

8 :10 Time required 

2 :46 Time required 

Al. Repeats 7 digits. (1 of 2. Order correct. Read 1 per second.) 
2-1-8-3-4-3-9 9-7-2-8-4-7-5 



THE STANFORD REVISION AND ITS HISTORY 21 

YEAR XVI, AVERAGE ADULT. (6 tests, 5 montlis each.) 

1. Vocabulary, 65 words. Score Total Vocab 

2. Interpretation of fables. (Score 8.) (First explain what a fable 

is, and after reading each say, "What lesson does that teach 

us?") 

a. Hercules and wagoner 

h. Maid and eggs 

c. Fox and crow 

d. Farmer and stork 

e. Miller, son and donkey 

3. Difference between abstract words. (3 real contrasts out of 4.) 

a. Laziness and idleness 

6. Evolution and revolution 

c. Poverty and misery 

d. Character and reputation 

4. Problem of the enclosed boxes. (3 of 4.) One large box con- 

taining: 

a. 2 smaller, 1 inside of each 

h. 2 smaller, 2 inside of each 

c, 3 smaller, 3 inside of each 

d. 4 smaller, 4 inside of each 

5. Repeats 6 digits backwards. (1 of 3.) 

4-7-1-9-5-2 5-8-3-2-9-4 7-5-2-6-3-8 

6. Code, writes "Come quickly." (2 errors. Omission of dot counts 

half error. Illustrate with "war," "trench," and "spy.") 

Errors C-O-M-E Q-U-I-C-K-L-Y Time 

Method 

Al. 1. Repeats 28 syllables. (1 of 2 absolutely correct.) 

a. Walter likes very much to go on visits to his grandmother, 

because she always teUs him many funny stories. 
6. Yesterday I saw a pretty little dog in the street. It had curly 
brown hair, short legs, and a long tail. 
Al. 2. Comprehension of physical relations. (2 of 3.) 

o. Path of cannon baU 



h. Weight of fish in water. 
c. Hitting distant mark. . . 



XVIII, SUPERIOR ADULT. (6 tests, 6 months each.) 

1. Vocabulary, 75 words. Score Total Vocab 

2. Binet's paper cutting test. Draws folds and locates holes. (If 

given, must come before XlVa.) 

3. Repeats 8 digits. (1 of 3. Order correct. Read 1 per second.) 

7-2-5-3-4-8-9-6. . . . 4-9-8-5-3-7-6-2. . . . 8-3-7-9-5-4-8-2. . . . 

4. Repeats thought of passage heard. (1 of 2. E. reads each in about 

3^ min.) "I am going to read you a Httle selection. Listen 
carefully, and when I am through I will ask you to tell as much 
of it as you can remember. Ready — " 



22 STANFORD REVISION OF BINET-SIMON SCALE 

a. "Tests such as we are now making are of value both for the 
advancement of science and for the information of the person 
who is tested. It is important for science to learn how people 
differ and on what factors these differences depend. If we can 
separate the influence of heredity from the influence of environ- 
ment we may be able to apply our knowledge so as to guide 
human development. We may thus in some cases correct 
defects and develop abihties which we might otherwise neglect." 



"Many opinions have been given on the value of life. Some call 
it good, other call it bad. It would be nearer correct to say 
that it is mediocre, for on the one hand our happiness is never as 
great as we should like, and on the other hand our misfortunes 
are never as great as our enemies would wish for us. It is this 
mediocrity of life which prevents it from being radically unjust." 



5. Repeats 7 digits backwards. (1 of 3.) 

4-1-6-2-5-9-3 3-8-2-6-4-7-5 9-4-5-2-8-3-7 

6. Ingenuity test. (2 of 3. 5 minutes each. If S fails on 1st, E 

explains that one.) 
a. "A mother sent her boy to the river to get seven pints of water. 
She gave him a 3-pint vessel and a 5-pint vessel. Show me how 
the boy can measure out exactly 7 pints without guessing at 
the amount. Begin by filling the 5-pint vessel." 



h. Same, except 5 and 7 given to get 8. ("Begin with 5.") 
c. Same, except 4 and 9 given to get 7. ("Begin with 4.") 



THE STANFORD REVISION AND ITS HISTORY 



23 



Time required. 

1. orange. . . . 

2. bonfire 

3. roar 

4. gown 

5. tap 

6. scorch 

7. puddle 

8. envelope. . 

9. straw 

10. rule 

11. haste 

12. afloat 

13. eye-lash. . . 

14. copper. . . . 

15. health 

16. curse 

17. guitar 

18. mellow 

19. pork 

20. impolite. . . 

21. plumbing. 

22. outward. . , 

23. lecture. . . . 

24. dungeon. . 

25. southern. . 

26. noticeable. 

27. muzzle 

28. quake 

29. civil 

30. treasury. . , 
31 . reception. . 

32. ramble 

33. skni 

34. misuse. . . . 

35. insure 

36. stave 

37. regard. . . . 

38. nerve 

39. crunch 

40. juggler 

41. majesty. . . 

42. brunette. . 

43. snip 

44. apish 

45. sportive. . . 

46. hysterics. . 

47. Mars 

48. repose 

49. shrewd 



THE VOCABULARY TEST 

Score 

51. pecuHarity 

52. coinage. 

53. mosaic 

54. bewail 

55. disproportionate. 

, 56. dilapidated 

, 57. charter 

, 58. conscientious ... 

, 59. avarice 

60. artless 

61. priceless 

62. swaddle 

63. tolerate 

64. gelatinous 

65. depredation 

66. promontory 

67. frustrate 

68. milksop 

69. philanthropy 

70. irony 

71. lotus 

72. drabble 

73. harpy 

74. embody 

75. infuse 

76. flaunt 

77. declivity 

78. fen 

79. ochre 

80. exaltation 

81. incrustation. . . . 

82. laity 

83. selectman 

84. sapient 

85. retroactive 

86. achromatic 

87. ambergris 

88. casuistry 

89. paleology 

90. perfunctory 

91. precipitancy. . . . 

92. theosophy 

93. piscatorial 

94. sudorific 

95. parterre 

96. homunculus .... 

97. cameo 

98. shagreen 

99. limpet. 



50. forfeit 100. complot 

Note : To get the entire vocabulary, multiply the number of correct 
definitions by 180. 



24 STANFORD REVISION OF BINET-SIMON SCALE 

The Fable Test 

"Fables, you know, are little stories which teach us a lesson. Now 
I am going to read a fable to you. Listen carefully and when I am 
through I will ask you to tell what lesson the fable teaches us." 

After reading each fable say, "What lesson does that teach us?" 
Ask also if fable has been heard before. 

A. Hercules and the Wagoner 

A man was driving along a country road, when the wheels suddenly 
sank in a deep rut. The man did nothing but look at the wagon and 
call loudly to Hercules to come and help him. Hercules came up, 
looked at the man, and said: "Put your shoulder to the wheel, my 
man, and whip up your oxen." Then he went away and left the driver. 
Lesson 

B. The Milkaiaid and Her Plans 

A milkmaid was carrying her paU of milk on her head, and was 
thinking to herself thus: "The money for this milk will buy 4 hens; 
the hens will lay at least 100 eggs; the eggs will produce at least 75 
chicks; and with the money which the chicks will bring I can buy a 
new dress to wear instead of the ragged one I have on." At this mom- 
ent she looked down at herself, trying to think how she would look in 
her new dress ; but as she did so the pail of milk slipped from her head 
and dashed upon the ground. Thus all her imaginary schemes perished 
in a moment. 
Lesson 

C. The Fox and the Crow 

A crow, having stolen a bit of meat, perched in a tree and held it 
in her beak. A fox, seeing her, wished to secure the meat, and spoke 
to the crow thus: "How handsome you are! and I have heard that the 
beauty of your voice is equal to that of your form and feathers. Will 
you not sing for me, so that I may judge whether this is true?" The 
crow was so pleased that she opened her mouth to sing and dropped 
the meat, which the fox immediately ate. 
Lesson 

D. The Farmer and the Stork 

A farmer set some traps to catch cranes which had been eating his 
seed. With them he caught a stork. The stork, which had not really 
been steahng, begged the farmer to spare his life, saying that he was 
a bird of excellent character, that he was not at all like the cranes, and 
that the farmer should have pity on him. But the farmer said: "I 
have caught you with these robbers, the cranes, and you have got to 
die with them." 
Lesson 



THE STANFORD REVISION AND ITS HISTORY 25 

E. The Miller, His Son, and the Donkey 

A miller and his son were driving their donkey to a neighboring 
town to sell him. They had not gone far when a child saw them and 
cried out: "What fools those fellows are to be trudging along on foot 
when one of them might be riding." The old man, hearing this, made 
his son get on the donkey, while he himself walked. Soon they came 
upon some men. "Look," said one of them, "see that lazy boy riding 
while his old father has to walk." On hearing this the miller made his 
son get off, and he chmbed upon the donkey himself. Farther on they 
met a company of women, who shouted out: "Why, you lazy old 
fellow, to ride along so comfortably while your poor boy there can 
hardly keep pace by the side of you!" And so the good-natured 
miller took his boy up behind him and both of them rode. As they 
came to the town a citizen said to them, "Why, you cruel fellows! 
you two are better able to carry the poor donkey than he is to carry 
you." "Very well," said the miller, "we will try." So both of them 
jumped to the ground, got some ropes, tied the donkey's legs to a pole 
and tried to carry him. But as they crossed the bridge the doiJiey 
became frightened, kicked loose and fell into the stream. 
Lesson 



CHAPTER II 

THE DISTRIBUTION OF INTELLIGENCE 

The question as to the manner in which intelligen^^e 
is distributed relates itself at once to fundamental 
issues in biological theory and suggests social and 
educational problems of great importance. Perhaps 
the most vital question which can be asked by any 
nation of any age is the following: ^^How high is the 
average level of mental endowment among our people, 
and how frequent are the various grades of ability 
above and below the average?'' 

With the development of standardized intelligence 
tests we are approaching, for the first time, a possible 
answer to this question. The future of such tests is 
guaranteed by the importance of the problems which 
they undertake to answer. This would still be true 
even if it could be shown that all the mental tests 
which have yet been devised or suggested are of little 
worth. 

Difficulties in Finding the True Distribution of Intelli- 
gence 

In view of the large number of investigations mad 
with the Binet-Simon tests in many countries, the 
light which these have thrown upon the distribution 
of intelligence is less than might have been expected. 
The reasons for this are various. In the first place, 
the number of children tested by any one investigator, 
and particularly the number at any one age, haB 
usually fallen short of that required for far-reaching; 
conclusions. If we could mass the results of different 
investigators the problem would be made much easier; 

26 



THE DISTRIBUTION OF INTELLIGENCE 27 

but owing to the lack of uniformity in the methods by 
which the data have been secured, this is usually a 
dangerous procedure. Because of the small numbers 
we can seldom be sure that the children tested were 
representative. Educational advantages, social status, 
racial differences, and other possible selective influences 
must be taken into account. To get representative 
children of a given age is especially difficult, and it is 
by no means easy even when questions of education, 
social status and race have been eliminated. Studies 
of the progress of school children through the grades 
have shown that children of any given age are scattered 
over an astonishing range of grades. It has been a 
common mistake to select certain school grades for 
the testing and to suppose that the results secured 
could be used as norms for the ages found in those 
grades. 

One factor or another has entered to impair the 
value of almost every experiment with the scale. 
Kuhlmann, for example, in his tests of 1000 children, 
avoided selection by examining all the children enrolled 
in the public schools of a small middle-class city; but 
Ms examiners were untrained. Fewer tests by trained 
examiners would have made his experiment of greater 
value in several respects. Binet's 1908 scale was based 
on tests of only 200 children, 15 to 25 of each age, and 
these were situated in one of the poorest quarters of 
Paris. What further selection of subjects took place 
in this experiment we are not informed. Bobertag's 
subjects were in the main pupils attending the Volks- 
sdiule, and these are known to have a lower average 
L 5vel of mental endowment than pupils attending the 
higher schools. Goddard^s numbers were fairly large, 
but the tests were made by persons of limited training 
and at a rate (as high as thirty per day for one tester) 



28 STANFORD REVISION OF BINET-SIMON SCALE 

which rendered thoroughness impossible. Some of 
the tests of Terman and Childs were made by only 
partly-trained examiners, and here, again, too little 
attention was paid to social class and age selection. 

In hke manner it would be easy to point out serious 
shortcomings in every study which has been made 
with the Binet scale, including those of Jeronutti at 
Rome, Treves and Saffiotti at Milan, Dr. Anna Schu- 
bert at St. Petersburg, Mrs. Wolkowitsch at Moscow, 
Bloch and Preiss at Kattowitz, Miss Johnston at Shef- 
field, Winch in London, Rogers and Mclntjrre at 
Aberdeen, Decroly at Brussels, Levistre and Morle in 
Paris, Miss Dougherty in Kansas City, Dr. Morse and 
Miss Strong in South Carolina, Dr. Rowe in Michigan, 
the Weintrobs in New York City, Dr. Schmidt in 
Chicago, etc. 

But even had the procedure and the method of 
selecting cases not been at fault in these studies, the 
results would still have been misleading as regards 
the distribution of intelligence, owing to the acknowl- 
edged imperfection of the scale used. The arrange- 
ment of tests in the earlier years magnified decidedly 
the amount and range of superior ability, and to a 
corresponding degree covered up the presence of re- 
tardation. At the upper end of the scale the tests 
were so few and so unsatisfactory that individual 
differences above the level of eleven years were hardly 
brought out at all. Only at the middle point was the 
scale reasonably accurate. 

As regards the distribution of intelligence we believe 
that the Stanford 1914-1915 data have more than 
ordinary significance, and for reasons which it may be 
well to enumerate: 

(1) The children were as nearly representative of 
the different ages as it is possible to get. The method 



THE DISTRIBUTION OF INTELLIGENCE 29 

was to select a school attended by all the children of 
school age in the community, and to test the children 
of the various ages in whatever grades they might 
happen to be. This obviates accidental age selection 
at least for the years 7 to 13, inclusive. It is possible, 
however, that six-year-old and fourteen-year-old school 
children are not quite representative of children of 
those ages, since mentally retarded six-year-olds are 
likely to enter school a year late and since a consider- 
able number of fourteen-year-olds have been promoted 
to the high school. 

(2) The children tested were all within two months 
of a birthday. Our curve of distribution for nine- 
year intelhgence, for example, really represents the 
distribution of intelligence for nine-year olds, and not 
that of children ranging all the way from eight and a 
half to nine and a half years. 

(3) The schools selected for the tests were such as 
almost any one would classify as middle-class. Few 
children attending them were either from very wealthy 
or very poor homes. The only exception to this rule 
was in the case of Reno, where all the children within 
two months of a birthday were tested throughout 
the city. The large majority of these, however, were 
from homes of average wealth and culture. Only 2 
per cent., in fact, were classified by the teachers as of 
^'very inferior" social status, and only 1.6 per cent, as 
of ^'very superior" social status. 

(4) Care was taken to avoid racial differences and 
the difficulties due to lack of familiarity with the 
language. None of the children was foreign-born 
and only a few were of other than western European 
descent. The names were chiefly English, Irish, 
Scotch and German, with a few Swedish, French, 
Spanish, ItaUan, and Portuguese. Tests of Spanish, 



30 STANFORD EEVISION OF BINET-STMON SCALE 

Italian and Portuguese children were eliminated from 
our study of distribution, for the reason that in west- 
em cities children of these nationalities are likely to 
belong to unfavorably selected classes. We are justi- 
fied in beheving, therefore, that the distribution of 
intelligence among our subjects is less influenced by 
extraneous factors than has been the case in other 
studies of this kind. 

(5) The numbers tested were relatively large, 
namely 80 to 120 at each age from 6 to 14 years, with 
somewhat fewer at 5 and 15. Moreover, the use of 
only such children as were within two months of a 
birthday greatly enhances the value of the numbers 
employed. In each school this near-birthday group 
composed approximately one-third of all the children 
in attendance, and by the laws of chance we can be 
sure that the results are approximately as they would 
have been had the entire school enrollment been 
tested, that is, 3000 instead of 1000. This plan has the 
further advantage that three times as many schools 
were sampled as would otherwise have been the case; 
and if it happened, in spite of the care exercised, that 
some of the schools were below average in social status, 
this would probably be counterbalanced by other 
schools somewhat above average. 

(6) The scale by which the mental ages were com- 
puted is certainly much more accurate than Binet's 
or the earlier revisions. As already stated, the tests 
were worked over until the average mental age se- 
cured at each level approximately coincided with the 
physical age. In this way the scale was made of 
nearly equal accuracy at every point. 

(7) Correcting the rather large error of the scale 
at the upper and lower ranges gives another advantage 
of extreme importance, for it enables us to combine 



THE DISTEIBUTION OF INTELLIGENCE 31 

the intelligence quotients of the children of all ages 
into a single surface of distribution. As long as in- 
telligence was reckoned in terms of years and months 
of retardation or acceleration it was of course not 
permissible to combine the distributions for different 
ages. The range of mental ages is approximately 
twice as great at 10 years as at 5 years, so that one 
year of retardation or acceleration at 5 is equivalent 
to two years of retardation or acceleration at 10. Ac- 
cordingly, to combine the results for children of several 
different ages so as to show what percent of the entire 
number are retarded or accelerated one year, two 
years, three years, etc., is an absurd procedure. The 
range of intelligence quotients, however, as measured 
by the revised scale, is not far from constant from 
five to fourteen years, and these may therefore be 
combined into a single surface of distribution. The 
curve thus obtained differs from those of the indi- 
vidual years only in being somewhat more regular. 

(8) Finally, though by no means least in importance, 
the tests from which the following curves of distribu- 
tion were derived were made with more than ordinary 
care. The examiners were trained, the procedure was 
kept as uniform as possible and the scoring was all 
done by one person. Wherever evidence was found 
of mistaken procedure, the examiner was questioned, 
and if the records of that examiner for that test were 
not comparable with the others, they were thrown 
outv 

After making the necessary eliminations because of 
incomplete testing, foreign parentage, etc., there 
remained 981 children, distributed as shown herewith, 

TABLE 2 

Age 4 5 6 7 8 9 10 11 12 13 14 15 16 

Cases.... 16 54 117 92 100 113 87 97 83 98 82 46 14 



32 STANFORD REVISION OF BINET-SIMON SCALE 

The Distribution of Intelligence for the Ages Separately 

The intelligence quotients were calculated for all 
the children and those for a given year were then 
thrown into groups so that each group represented 
the cases include in a range of ten points intelligence 
quotient. The middle group includes the intelligence 
quotients from 96 to 105; the ascending groups include 
in order those from 106-115, 116-125, 126-135, and 
136-145. The corresponding descending groups are 
86-95, 76-85, 66-75, and 56-65. Only one case tested 
below 56, a girl of 8 years who had an intelligence 
quotient of 51. None tested above 145. Graphs 1 to 
13 show the results of this grouping for each age sepa- 
rately from 4 to 16. 

It is evident at a glance at these graphs that the 
distribution of intelligence quotients is fairly sym- 
metrical at each age from 5 to 14. At 14 the number 
of exceptionally superior children decreases, as we 
should expect, since a few of the brightest have by 
that age finished the eighth grade. At 15 the intelli- 
gence quotients range on either side of 90 as a median, 
and at 16 years on either side of 80 as a median. 
This, again, is what we should expect, because we 
know from other facts that a majority of school 
retardates are below average in intelligence. The 17 
4-year-olds averaged high, with a median intelligence 
quotient of 103. It is reasonably certain, however, 
that children of this age attending school are usually 
somewhat beyond the average in intelligence. 

It will be noted that at every year from 5 to 14 the 
middle group is the largest and that the groups on 
either side decrease in size somewhat regularly with 
increasing distance from the median. In the lower 
years, however, the 106-115 and 116-125 groups are 
larger than the 86-95 and 76-85 groups respectively 



THE DISTKIBUTION OF INTELLIGENCE 



33 



5&-65 66-7S 7G-8S 86-SS 9G-I05 lOG-IIS ilB-lZS l2Q>-ldS l5Q-/fS 

9'Jo lyi. 327. zn, 18I0 f'h 

Graph 1. Distribution of intelligence quotients of 16 kindergarten 
children, age 4 years. (These pupils are a selected group and 

test high.) 



J<S-65 66-7s5" r&'S5 86-95 SS-IOS lO&'llS II&-12S l2e-l3S I3&-I'f-S 

/Z.S7, 2S% 37.S'/. I2S7. 01 1251. 

Graph 2. Distribution of intelligence quotients of 54 kindergarten 
children, age 5 years. ^(Median at 102.) 



34 STANFORD REVISION OF BINET-SIMON SCALE 



5G'G5 G6-7S 76-85 8&- 35 9B-I05 lOb-llS ll(o-lZ5 IZ&-I35 IZ&-lfS 
It 67. 177. 387. 2fX, 37. 67. a 

Gkaph 3. Distribution of intelligence quotients of 117 unselected 
6-year-olds. (Median at 103.) 



.56 -G5 66- 75 76 -85 86 -95 % -105 106 -1/5 J/6 -/Z6 126-155 /56-I4-5 
2'/. 337. 175'/. 35'/. 277. // 7. 337. I7. 

Gbaph 4. Distribution of intelligence quotients of 93 unselected 
7-year-olds. (Median at 102.) 



THE DISTRIBUTION OF INTELLIGENCE 35 



S6-6S Ge-73 7G-8S 8B-96 36 -105 lOG-llS 116 -126 IZB-135 136 ■/4-S 
I'/o 07, 7 'A 16.5'/. '^07, £0.5'/. /£'/. 3% 

Graph 5. Distribution of intelligence quotients of 98 unselected 
8-year-olds. (Median at 101+.) 



56 -65 66 - 75 7&-8S 86 SS' 96 - /OS/06 -//S 116 -126 1 Z6- 135136 -/'fS 
2 7. /^7. 211. 38'/. Z3.51 6'/. I'l. /'/. 

Graph 6. Distribution of intelligence quotients of 113 unselected 
9-year-olds. (Median at 100.5.) 



36 STANFOKD REVISION OF BINET-SIMON SCALE 



I I 



5G -es GG-7S 76-B5 86 -9S 96 -105 106 -I IS 116 -126 1 26 -135 /36-/4'S 
2.3 7. 257, J8.S'/. Jf*/. 2G7. 14-7. 17. /'A 

Graph 7. Distribution of intelligence quotients of 87 unselected 
10-year-olds. (Median at 103.) 



c 



D 



5&-65 66 -TS 76-85 86-95 96 105 I06-J/5 Ii6-I25 /26-/35I3G-/4-5 
l.3'J, 25% 63'/. 2031 32'/. 2/7'/. ii57. 4-'/. /.37. 

Graph 8. Distribution of intelligence quotients of 79 unselected 
11-year-olds. (Median at 98.) 



^6-65 66-75 76-85 86-95 96-105 lOe-iiS 116-125 126-/35 /J^-//-^ 
57, 157, 20.57. 287. 1957, li'l. S 7. 

Graph 9. Distribution of intelligence quotients of 83 unselected 
12-year-olds. (Median at 98.) 



THE DISTRIBUTION OF INTELLIGENCE 37 



56 -es 66 -ZS 76-85 86-35 96-105 106-115 116-125 126-135 I3G-I4'S 
/'/, 71 ll'L 2257. 337. 1857^ 67. 17, 

Graph 10. Distribution of intelligence quotients of 98 unselected 
13-year-olds. (Median at 96.5.) 

A few of the brightest 13-year-olds had been eliminated from this 
group by promotion to the high school and were not tested. 



56-65 66-75 76-8586-95 36-105 106-115 IIG- 125 I2Q-I35 136-/^5 
25 7. 12 7. 2557. Jf7, 22% 5 71 

Graph 11. Distribution of intelligence quotients of 82 children 14 

years of age. (Median at 97+.) 

Many of the brightest 14-year-olds had been promoted to the high 
school and do not appear in the above graph. 



38 STANFORD REVISION OF BINET-SIMON SCALE 



C 



5G-6S bh-75' 76-8S 8G-9S S6-/0S /0(>-//S //6 -/^S /2G-/JS /J6-/¥-J^ 
Z'l, (o'l. Zb'l. it'/. 26'/. ^°'. 

Graph 12. Distribution of intelligence quotients of 47 children, age 
15 years (over-age for grade). (Median 90.) 

Most of the average and superior 15-year-olds had been promoted 
to the high school and do not appear in the above graph. 



5Q>-^5 G€>-7S 
/f/. 2Z'/. 

Graph 13. 



7G-8S 86 -3S $6 -tOS lOb -US /Ib-IZS IZC ■IJS/3^-/4-S 

35'/, zru 7% 



Distribution of intelUgence quotients of 14 children, age 
16 years (over-age for grade). (Median 80.) 
AH of the average and superior 16-year-olds had been promoted to 
the high school and do not appear in the above graph. 



THE DISTRIBUTION OF INTELLIGENCE 39 

on the other side. The most noticeable lack of sym- 
metry occurs at ages 5, 6, and 14. This is due in part 
to a certain amount of unavoidable selection. The 
five-year-olds were enrolled in kindergartens, and since 
school attendance at this age is not compulsory, we 
can not be sure that kindergarten children represent 
the median intelligence for five-year-olds. The same 
is true of six-year-olds, though to a less extent. In 
both cases the distribution of intelligence quotients 
suggests that at these ages inferior children are some- 
what less likely to be found in school than those of 
superior endowment. The reverse is the case at 14, 
since a few of the brighter children of that age have 
completed the eighth grade and have either dropped 
out or passed on to the high school. It is possible 
that a few children under 14 have managed to evade 
the compulsory attendance laws and are not in school, 
but it is certain that in the cities and towns where our 
testing was done the amount of such evasion was 
practically negligible. 

On the whole, it is evident that the distribution of 
intelhgence quotients is fairly regular and uniform in 
the various years. This is further shown by the fact 
that the range including the middle 50 percent of the 
intelligence quotients does not vary greatly between 
5 and 14 years. Combining each two successive years 
in order to overcome the chance effects of the limited 
number of children of any one age, we have the ac- 
companying table in which, it is of interest to note, 
the distribution of intelligence quotients for the differ- 
ent age-levels furnishes no support to the very generally 
accepted belief that variability materially increases at 
adolescence. As far as 14, at least, there is no evidence 
that this occurs. 



40 STANFORD REVISION OF BINET-SIMON SCALE 





TABLE 3 






Limits of quotient 


Range of quotients 


Ages 


including middle 50% 


including middle 50% 


5 and 6 combined 


97 to 111 


15 


7 and 8 combined 


95+ to 111 


16+ 


9 and 10 combined 


94 to 108 


15 


11 and 12 combined 


92 to 108 


17 


13 and 14 combined 


90 to 105 


16 



All ages combined 92+ to 108 16+ 

The Distribution of Intelligence for the Ages Combined 

As already explained, the corrected scale has the 
advantage of enabling us to combine the intelligence 
quotients of the children of different ages into a single 
surface of distribution, something that we could not 
do when the scale was too easy at some levels and 
too hard at others. By combining ages 5 to 14, we 
have the distribution shown in Graph 14. Ages 4, 15 
and 16 have been omitted from this combined dis- 
tribution because of the selection which has taken 
place at these years. ^ 



S6'GSGG-rS 7G-8S 8e-9S SG-/05 /0&-//S //G-/£^ /2e-/JSf36-/^5' 
.337. 2.37. 8.GX 20./7. JJ.S'A 23J7. 901 zyL ^Sl 

Graph 14. Distribution of intelligence quotients of 905 unselected 
children, ages 5-14 years. (Median at 99.) 



^ At 15 and 16 there is the additional reason, that growth at this 
time is probably slowing down suflSciently to impair the vaUdity of the 
intelligence quotient. 



THE DISTRIBUTION OF INTELLIGENCE 



41 



Exception may be taken to this combined distribu- 
tion on the ground that it fails to take account of 
possible selection which may have taken place at ages 
5, 6, 13, and 14. As shown in Graph 15, however, the 
distribution for ages 7 to 12 combined is little different 
from that for 5 to 14 combined. 



f£-G5 G6'7S 7e-B5 8&-35 9G-I0S J0&-I15 l/G-125 {ZS-/35 /3Q-li-5 
XL 1:87. 8% 13'/. Jjr. EiJ'L 3.81 Z'L 7'A 

Graph 15. Distribution of intelligence quotients of 554 unselected 
children 7-12 years of age. (Sexes combiaed.) 

TheHntelligence quotients may, of course, be grouped 
in ranges of any desired extent. If the numbers dealt 
with had been larger, it would have been interesting 
to group them in ranges of 5 instead of 10. With the 
numbers available, however, the curves resulting [from 
this method of grouping would be much less regular than 
when larger groups are used. On the other hand, if 
ranges above 10 are used for the grouping, the distri- 
bution becomes still more symmetrical. This may 
be seen from Graph 16, which shows the relative sizes 
of groups contained in ranges of 20, for ages 5 to 14 
combined. 



42 STANFORD REVISION OF BINET-SIMON SCALE 




Graph 16. Distribution of intelligence quotients of 905 unselected 
children, age 5-14 years. Intelligence quotients grouped in 

ranges of 20. 

Followdng is a comparison of the observed distri- 
bution (Ages 5-14) with that called for by the theoretical 
normal" curve of distribution (the Gaussian curve): 

TABLE 4 

Intelligence Quotient Ranges 



(( 



Obtained 
Theoretical 



56-65 



.33 
.4 



66-75 



2.3 
3.1 



76-85 



8.6 
11. 



86-95 



20.1 
22. 



96-105 



33.9 
27. 



106-115 



23.1 
22. 



116-125 



9. 
11. 



126-135 



2.3 
3.1 



136-14? 



.55 
A 



The normal nature of the distribution of mental 
ability is further borne out by the teachers' rankings 
according to intelligence and school work, which were 
made according to the form given in the appendix. 
These rankings were made in a httle more than half 



THE DISTRIBUTION OF INTELLIGENCE 



43 



the schools and included 489 children, about equally 
divided between the sexes. The results are shown on 
page 48. 

The distribution shown in the graphs of this chapter 
are for the boys and girls combined. There are cer- 
tain sex differences, however, which will be set forth 
in Chapter III. We may ignore these for the present, 
since they are not great, and proceed to an examination 
of the frequency with which various departures from 
the normal are encountered. 

An examination of the distribution for all the ages 
from 5 to 14, taken together, and for the sexes com- 
bined, gave the following significant facts: 

TABLE 5 
rhe lowest 1 percent go to 70 or below; the highest 1 percent reach 130 or abov 



2 




3 




5 




10 




15 




20 




25 




33.3 





u u 73 . 




a 2 


u 128 " " 


u u 75 c 




u 3 


u 125 " " 


u u 7g c 




a 5 


u 122 " " 


u u g5 i 




" 10 " 


u 115 u u 


a u gg ^ 




u 15 u 


u 113 u u 


a u 91 . 




" 20 " 


u 110 u u 


" " 92+ ' 




" 25 " 


U IQg u u 


" " 95 ' 




" 33.3 " 


" 106+ " " 



A perfectly normal distribution would cause 93 per- 
cent of the cases to fall between 76-125, instead of 
the observed 94.7 percent; and 99.2 percent between 
66-135, instead of the observed 99.3 percent. 

Or, to put some of these facts of distribution in 
another form, we may say, speaking approximately: 

The child reaching 110 is equaled or excelled by 20 out of 100 

u a u 115 u u u u u iQ u u jqq 

" " " 125 " " " " " 3 " " 100 

II II (I 1^0 " '' " '' " 1 " " 100 

Again, for those whose intelligence quotient is below 
100: 

The child testing at 90 is equaled or excelled by 80 out of 100 

u u u u g5 U U U U U 9Q u u iQo 

it cc (c li 75 a a a (i u 07 ce ci lAT) 

a (( ii (I 7Q II u ii a li QQ a n iqq 



44 STANFORD REVISION OF BINET-SIMON SCALE 

When we examine the above data, it is difficult to 
avoid the conclusion that superior intelligence of any 
given degree occurs with approximately the same 
frequency as intelligence which is inferior to a corres- 
ponding degree. The usual assumption, however, is 
that extreme degrees of mental deficiency are much 
more numerous than extreme degrees of mental 
superiority. As far as intelligence quotients between 
60 and 140 are concerned, our figures do not support 
this assumption.2 As regards the relative frequency 
of intelligence quotients below 60 and above 140, the 
assumption is in all probability valid; for while all idiot 
and most imbecile children have an intelligence quotient 
as low as 50, there are extremely few cases of budding 
genius which reach as high as 150. Indeed, notwith- 
standing diligent search, the writer has found only a 
few cases testing above 150, and only two testing as 
high as 170.3 

The significance of various intelligence quotients 
will be dealt with more fully in another chapter. It is 

2 This statement requires some modification in view of the fact that 
om* data were collected entirely from children who were attending 
pubHc schools. There are, of com-se, in any community a few children 
with inteUigence quotients between 60 and 80 who are either kept at 
home or placed in institutions. No investigation seems to have been 
made which would show what proportion of such children are not in 
school, but our experience suggests that it is very small. At any rate, 
relatively few children testing as high as 65 or 70 are sent to an institu- 
tion until they have first been tried for several years in the schools, 
usually until well toward adolescence. It is well known that only a small 
minority with an inteUigence quotient of 75 to 80 ever get into an 
institution for the feeble-minded. 

3 This is not to deny that cases of considerably higher intelUgence 
quotient are to be found. A five-year-old child reported by Miss 
Langenbeck seems to have tested not far from ten years. If the test 
can be accepted at its face value, the child, therefore, had an intelhgence 
quotient of about 200. See A study of a five-year-old child, Pedag. 
Seminary, March, I9I5, 65-88. More recently Dr. Leta S. Holhng- 
worth has favored us with a copy of a test of an eight-year boy whose 
inteUigence quotient is 190. 



THE DISTEIBUTION OF INTELLIGENCE 45 

already evident, however, that the term '^ feeble- 
mindedness '^ is a matter of arbitrary definition. In 
one sense it could be said that a child with an intelli- 
gence quotient of 85 or 90 is as truly feeble-minded as 
one testing at 50, only he is mentally feeble to a much 
less degree. It becomes merely a question of the 
amount of intelligence necessary to enable one to get 
along tolerably with his fellows and to keep somewhere 
in sight of them in the thousand and one kinds of 
competition in which success depends upon mental 
ability. The definition of feeble-mindedness, too, is 
a constantly shifting one. Until recent years the 
standard was one which would have classed a majority 
of children having two-thirds intelligence (intelligence 
quotient 67) in the normal group. Even yet the usual 
medical standard is no higher than this. The child 
of moron grade is rarely classified by the physician 
as ^' feeble-minded." Social workers, psychologists, 
and criminologists, however, are constantly meeting 
facts which would seem to justify the application of 
the term feeble-minded to many children with three- 
fourths intelligence (intelligence quotient 75). It is 
possible that the development of civilization, with 
its inevitable increase in the complexity of social and 
industrial life, will raise the standard of mental nor- 
mality higher still. 

But whatever the standard, the number of borderline 
and debatable cases will probably be greater than the 
number of those whom all would agree to call feeble- 
minded. The attempt to classify all children as either 
definitely feeble-minded or definitely normal involves 
exactly the same difficulties as we should encounter 
in trying to classify all adult men as either ^'normally 
tall'' or ^ ^abnormally short," and we may add that 



46 STANFORD REVISION OF BINET-SIMON SCALE 

the one attempt is just about as much worth while 
as the other. 

To regard feeble-inteUigence as always a disease, 
which, like small-pox, one either has or does not have, 
is a view which is contradicted by all we know about 
the distribution of mental traits. Physicians find 
special difficulty in freeing themselves from this fallacy, 
since for them diagnosis consists essentially in deter- 
mining the presence or absence of definitely patho- 
logical conditions. 

There is other evidence than that of mental tests 
to support the hypothesis that intelligence is dis- 
tributed in the manner indicated by oiu" distribution 
of intelligence quotients. It has often been shown 
that a similar distribution results when teachers are 
asked to classify children into three groups (or five 
groups) according either to school success or intelli- 
gence. Thus, Bobertag had teachers classify 2772 
pupils into three groups according as their school 
work was '^unsatisfactory," '^ satisfactory," or '^ better 
than satisfactory. ' ' The resulting classification showed 
50.8 percent in the middle group, 25.7 percent in the 
superior group, and 23.5 percent in the inferior group. 
The numerous other studies which have been made 
of teachers' marks give similar results, though in 
some cases the curve shows a more noticeable tendency 
to be skewed in the direction of superiority. 

About half our teachers supplied for each of their 
children tested the supplementary data called for on 
the blank shown in the appendix. It will be noted 
that Question 4 calls for a classification of the children 
into five groups according to the quality of school 
work, and Question 5 a similar classification on the 
basis of the teacher's judgment as to a child's intelli- 



THE DISTRIBUTION OF INTELLIGENCE 47 

gence. The classes were designated in the blank as 
"very inferior/' "inferior," "average/' "superior" 
and "very superior." The resulting distributions 
are shown herewith. 

TABLE 6 
Percents Rated 
Very Very 
Inferior Inferior Average Superior Superior 
Schoolwork (503 Chil- 
dren) 5.2 17.9 51.0 22.1 3.8 

Teacher's judgment of 
intelligence (489 
Children) 3.4 14.4 55.8 23.1 3.3 

If for quality of school work, we combine the two 
superior groups and combine similarly the two inferior 
groups, the distribution coincides remarkably with 
that found by Bobertag. 

TABLE 7 

Inferior 

Bobertag 23 . 5 

Ours 23.1 

It is interesting to compare the teachers' groupings 
for intelligence with those for school success, as shown 
in Graphs 17 and 18. 

The "piling up" of the intelligence distribution 
in the direction toward the "superior" end indicates 
that teachers are able to judge the degree of a child's 
intelligence less objectively and therefore less accu- 
rately than they judge the quahty of his school work. 
Personal factors are more likely to enter into judgments 
about intelligence, and in case of uncertainty as to 
the proper classification there is a natural tendency 
to give the child the benefit of the doubt, even at 
the risk of grading him too high.^ 

4 The relation between the inteUigence tests and the teachers' judg- 
ments of inteUigence is treated in full in Chapter VI. 



Average 


Superior 


50.8 


25.7 


51.0 


25.8 



48 STANFORD REVISION OF BINET-SIMON SCALE 



\/ery Inferior Jnjtnor Average Superior Very superior 
3.1-7. /f/f-y- 55 8'/. 23l'f. 33'/r 

Graph 17. Distribution of teachers' rankings of 489 children ac- 
cording to intelligence. 



Very Inferior Inftnor Average Superior Very superior 
5.Z% 17.97. 51'/. 221'/. 3.81 

Graph 18. Distribution of teachers' rankings of 503 children" ac- 
cording to quaUty of school work. (Mostly the same children as 
appear in Graph 17.) 



THE DISTRIBUTION OF INTELLIGENCE 49 

The ''Mental Ages'' of 62 Normal Adults 
The use of the Stanford revision with 30 business 
men of moderate success and of very limited educa- 
tional advantages gave a distribution of mental ages 
differing Uttle from that found with 32 high school 
pupils pupils from 16 to 20 years of age. The results 
for both groups are shown in tabular form. 

TABLE 8 
Mental Age 

13 to 14 to 15 to 16 to 17 to 18 to 

13-11 14-11 15-11 16-11 17-11 18-11 

Business Men 1 6 7 8 6 2 

H. S. Pupils 5 12 10 4 1 

If we combine the business men with the high school 
pupils who are over 16 years of age chronologically, 
we have the distribution of mental ages shown in 
Graph 19. It will be noted that the middle part of 
the graph represents the "mental ages'' falUng within 
the range of two years, namely 15 to 17. This range 
we may designate as the "average adult" level. 

Summary 

1. The revised scale gives a median intelHgence 
quotient of approximately 100 when used with unse- 
lected children of any age from 5 to 14. 

2. The distribution of intelligence quotients for 
unselected children of each age conforms fairly closely 
to the Gaussian curve. This holds particularly for 
our subjects of ages 7 to 13. 

3. Since the revised scale yields the same form of 
distribution of intelhgence quotients at each age, it 
is permissible to combine the intelhgence quotients 
for the different ages from 5 to 13 or 14 into a single 
surface of distribution. 

4. The mental ages found by testing 30 uneducated 
business men and 32 high school pupils over 16 years 
of age range from the "inferior adult" level to the 
"superior adult" level, with the greatest number at. 
"average adult." 



50 STANFORD REVISION OF BINET-SIMON SCALE 



l3to 13-11 H-U 1^-11 l5UiS-ll I7UI7-II iShlB'll 
LQr. nil, S9.77, IGZ'A 4-.SZ 

Gkaph 19. Mental ages of 62 adults, including 30 business men of 
little education and 32 high school students over 16 years of age. 



CHAPTER III 

THE RATE OF GROWTH AND THE VALIDITY 
OF THE INTELLIGENCE QUOTIENT 

The previous chapter showed that for unselected 
children the distribution of inteUigence as measured 
by the revised scale maintains a certain constancy 
from 5 to 13 or 14 years, when the degree of intelligence 
is expressed in terms of the intelligence quotient. Any 
given deviation from the median occurs with much 
the same frequency at all the ages. 

The intelligence of children has usually been esti- 
mated, however, in terms of years and months of 
retardation or acceleration. Binet, while using this 
method, realized that a year of retardation is less 
serious with older children than with younger, and 
accordingly he suggested the rule that while a retarda- 
tion of 2 years usually means feeble-mindedness in 
children under ten years of age, older children should 
not be regarded as feeble-minded unless retarded as 
much as 3 years. This is obviously crude, but Binet 
did not suggest any more definite adjustment to allow 
for the decreasing significance of a given amount of 
retardation in the upper years. Even this slight 
adjustment is often ignored by those who use the 
scale. One person, after testing a large number of 
juvenile delinquents ranging from 10 to 18 years in 
age, lumps all the ages together and counts up the 
number who were retarded 1 year, 2 years, 3 years, 
4 years, etc., concluding finally that about 75 percent 
of the total number were feeble-minded, since that 
many were retarded 3 years or more. This error 
appears again and again in the Hterature of Binet 
testing. Others, starting from the same erroneous 

51 



52 STANFORD REVISION OF BINET-SIMON SCALE 

assumption, have defined ^^at-age'' intelligence as 
that which is within one year of the child's physical 
age and have expected to find the number of children 
testing ^^at-age" to be the same at all chronological 
ages. 

It is obvious, however, from the distribution of 
intelhgence quotients as shown in Chapter II, that 
a given number of years of retardation can have no 
definite meaning except in relation to the age of the 
subject. Whatever the age of a group of non-selected 
children, approximately the same percent will always 
be included in any range of the intelligence quotients. 
As already shown, the middle fifty percent are at all 
ages included in the range of about 92 or 93 intelligence 
quotient to 108 or 109 intelligence quotient. Trans- 
muting these values into months, we have for 6-year- 
olds, 50 percent included in a range of a little less than 
one year of mental age; while for 12-year-olds, the 
middle 50 percent range over about twice this distance, 
or nearly two years. Retardation of two years is 
about as common at 12 years as retardation of one 
year at 6; and either is about as common as retardation 
of a year and a half at 9. That is, the curve of dis- 
tribution of mental ages becomes progressively flat- 
tened, the older the children with which we deal. 
This is shown in Graphs 20, 21, and 22, which give 
the distribution of mental ages for children of 6, 9, 
and 12 years, respectively. 

The range including 50 percent of the mental ages 
increases in a fairly constant ratio from Age 6 to Age 
14, as shown in Graph 23. 

The use of the intelhgence quotient as a means of 
expressing a child's intelligence status is based, of 
course, on the assumption that the intelligence quo- 



VALIDITY OF THE INTELLIGENCE QUOTIENT 53 




-3 -2 -/ 5-7 +1 +2 +3 

o7. 07. 7.37. 797. iZ'U 2.7% 7, 

Graph 20. Distribution of mental ages of the 117 iinselected 6-year- 
olds. 




-■f 


-3 


-2 


-1 


8-10 


+/ 


O'/o 


07o 


4-'/z '1, 


16 V, 


eo'/o 


/5% 



+ 2 



7. 



+ 3 



oy. 



Graph 21. Distribution of mental ages of the 113 unselected 9-year- 
olds. 




-•f -3 -2 -/ 11-13 +/ ^2 +3 +^ 

^7, 3.5% /2 7o !?'/> ^3 7o 1^3% 8.5% I'l. 07» 

Graph 22. Distribution of mental ages of the 83 imselected 12-year- 
olds. 



54 STANFORD REVISION OF BINET-SIMON SCALE 

Graph 23. Showing range of months including the middle 50% of 
mental ages at various years. 

tient remains practically constant during the years of 
mental growth; that, for example, the child of five 
years who tests at 4 (intelligence quotient 80) will 
at later ages have the mental ages shown in the follow- 
ing figures: 



10 


monThi 


13.4- 


monThs) 


J6 


mortThi 


zo 


■monThs 


ZG 


moTiThi 



TAB 


LE 9 








8 


9 10 11 


12 


13 


14 


6.4 


7.2 8 8.8 


9.6 


10.4 


11.2 



Physical Age 5 6 7 

Mental Age.... 4 4.8 5.6 6.4 7.2 

The facts which have already been presented argue 
in favor of the validity of the intelligence quotient 
at least for Ages 5 to 13 or 14. It has been shown 
that the distribution of intelligence quotients for 
the different years remains essentially the same, and 
that the distribution of mental ages (in terms of years 
and months) flattens out in the upper years in approxi- 
mately the expected ratio; 79 percent test within one 
year of physical age at 6, 60 percent at 9, and 43 
percent at 12. The percents called for at 9 and 12 by 
a theoretically valid intelligence quotient would be 
59.25 and 39.5, granting 79 percent to be correct for 



VALIDITY OF THE INTELLIGENCE QUOTIENT 55 

Age 6. The range of mental ages including the middle 
50 percent of cases is 10 months at Age 6, and increases 
in the succeeding years as shown in the accompanying 
table. 

TABLE 10 

Observed Percentage Percentage of In- 
Range Including of Increase Over crease Called for by- 

Age Middle 50 Percent That of Year 6 a TheoreticaUy VaUd 

Intelligence Quotient 

8 13.4 months 34 33.3 

10 16 months 60 67.6 

12 20 months 100 100 

The crucial test of the validity of the intelligence 
quotient would be to measure the intelligence of the 
same children several times during their period of 
mental growth. No experiment of this kind appears 
to have been made on any considerable scale, barring 
a few repetitions of tests after an interval of only one 
year. The results of such tests, however, support 
in a general way the hypothesis that the intelligence 
quotient of a given child tends to remain constant.^ 
The matter has been complicated, however, by the 
uneven inaccuracy of the Binet scale at different 
levels. 

Repeated tests are being made of a considerable 
number of children with the Stanford revision, and 
although the investigation is not complete at this 
writing, the results of 140 such tests show that as far 
as the age of 13 or 14, even when the tests are separated 
by as much as five years, changes of 10 points in 12 
are relatively rare. In general, it can be said that 
the superior children of the first test are found superior 
in the second, the average remain average, the inferior 

^ See W. Stern : Der Intelligenzquotient als Mass der kindlichen 
Intelligenz, inbesondere der unternormalen. Zeitsch. f. Angewandte 
Psychologie, 1916, Bd. II, Heft, 1-19. (Argues for the constancy of 
the inteUigence quotient from 7-12.) 



56 STANFORD REVISION OF BINET-SIMON SCALE 

remain inferior, the feeble-minded remain feeble- 
minded, and nearly always in approximately the 
same degree. The most marked exceptions to this 
rule are found with the feeble-minded, whose intelli- 
gence quotient shows a tendency to decrease consid- 
erably. 

If future investigations should confirm the validity 
of the intelligence quotient and its necessary corol- 
laries, the practical consequences would be of the 
greatest importance. It would mean that, after a 
mental test consuming no more time than an ordinary 
medical examination, the psychologist would be able 
to predict, with some degree of accuracy, the future 
of the child's mental development. There is nothing 
else which the average parent would more like to 
know about the child, and nothing else which would 
prove of greater value in directing its education. 

Whether the intelligence quotient holds even ap- 
proximately with very young children, or with children 
much beyond the age of 14, is a question on which 
the data available afford little light. We are war- 
ranted in believing, however, that general intelligence 
practically ceases to develop by the age of 18 or 20 
years. The mental age of high-grade morons appears 
to change little after the age of 14 or 15 years. With 
normal children development continues a little longer, 
though at a decreasing rate. It is practically certain, 
however, that growth of intelligence comes to a stand- 
still somewhere in the later years of adolescence, and 
that the cessation is gradual rather than sudden. It 
is evident, also, that beyond the time when the cessa- 
tion begins, the intelhgence quotient rapidly loses its 
meaning. The 12-year-old moron with a mental age 
of 8 years has an intelligence quotient of 67, which 



VALIDITY OF THE INTELLIGENCE QUOTIENT 57 

at this period of life probably indicates his mental 
status fairly well. When 6 years old, the same child 
probably had a mental age of about 4 years, and when 
9 years old, a mental age not far from 6 years. But 
inasmuch as mental growth slows down rapidly some- 
time after the age of 14 or 15, the mental age of this 
subject is unlikely ever to go beyond 10 years. Sup- 
posing it to stop at 10, the intelHgence quotient, if 
we continued to use it, would be reduced to 50 at 
the age of 20 years, to 25 at the age of 40 years, etc. 
Such a use of the term, of course, would be absurd, 
since the subject's intelligence is really a constant 
quantity throughout adult life. 

If it could be shown that mental growth continues 
its earlier rate up to a certain age, say 16, and then 
stopped quite suddenly, we could continue to use the 
intelligence quotient with adults of any age by merely 
ignoring the years beyond 16. That is, all adults, 
for purpose of reckoning the intelligence quotient, 
would be regarded as exactly 16 years of age.^ There 
are two difficulties, however, with a plan of this kind: 
(1) mental growth probably does not come to a stand- 
still suddenly; and (2) the time of its cessation is 
not accurately known. 

A practical way to get at the matter is to adopt 
some hypothesis of this general nature, a quite tenta- 
tive one, of course and by subjecting it to the pragmatic 
test of experiment, to see whether it is in harmony 
with ascertainable facts. If the hypothesis first 
adopted is unable to satisfy the requirements, it may 
be altered or replaced by a better. In this way, by 

2 Such a scheme would demand, however, that the upper end of the 
scale be so framed that the inteUigence of superior adults as well as 
that of superior immature subjects could be expressed in an intelligence 
quotient above 100. 



58 STANFORD REVISION OF BINET-SIMON SCALE 

checking up every step and profiting from our mis- 
takes, we should be able finally to arrive at a solution 
of the problem which would be correct enough for 
all practical piu-poses. 

Some of the data which have been presented would 
seem to justify the assumption, as a tentative working 
basis, that mental age maintains approximately a 
fixed ratio to chronological age until the latter has 
reached about 14 or 15 years, that during the next 
year or two the ratio diminishes, and that after the 
chronological age of 17 or 18 years, mental age re- 
mains constant. According to this hypothesis, the 
intelligence quotient would be a proper expression 
of the intellectual status with subjects as old as 14 or 
15 years. 

This is the hypothesis which has guided us in the 
extension of the scale at the upper end. We have at 
least succeeded in shaping it in such manner that a 
child, for example, whose mental age at 7 was 8 years 
(intelligence quotient about 115) will have at 14 a 
mental age in the neighborhood of 16 (intelUgence 
quotient about 115), with the possibility of further 
increasing his mental age considerably before growth 
ceases. Our high school students usually test between 
15 and 17 years, as do also Knollin's and Zeidler's 
business men. College students average slightl> 
higher, as we should expect from the fact that they 
belong to a selected group. 

It will be understood naturally that the numbers 
expressing such mental ages as 17 years, 18 years, 
19 years, etc., have only a conventional value and 
are not to be interpreted literally. Their use offers 
a feasible, if arbitrary, method of enabling the superior 
adolescent or adult to earn a quantitative expression 



VALIDITY OF THE INTELLIGENCE QUOTIENT 59 

of his superiority in the tests. Tentatively, we may 
use the intelligence quotient with normal adults by 
merely ignoring years of age beyond 16. That is, 
the adult^s chronological age is always, for this pur- 
pose, reckoned as 16. 

Further trial of our revision by repeating the tests 
between early and late adolescence, supplemented 
by tests of different groups of adults, will determine 
the adequacy of our arrangement. It is not offered 
as a finished product, but as material for further 
elaboration and refinement. 

Although the intelligence quotient maintains a 
fairly constant value from rather early in childhood 
until late in the growing period in the case of children 
of all grades of intelligence above mental deficiency, 
it is possible that this constancy may not be main- 
tained with defectives, particularly those of low grade. 
The child of 4 years who has a mental age of 1 year 
is an idiot and may never develop higher than a mental 
level of 2 years, perhaps not so high. His intelligence 
quotient of 25 at 4 years will gradually diminish, say 
to 15, at the age when mental maturity is attained in 
the normal child. We must look to the institutions 
where low-grade defectives are abundant to supply 
the facts regarding mental growth in these subjects. 

In closing this discussion it may be interesting to 
point out that the facts presented in this and the 
preceding chapter are not entirely in harmony with 
certain wide-spread opinions about the rate of mental 
growth. The view has often been expressed that 
intelligence normally develops by alternate leaps and 
rests. Starting from observations on certain instincts, 
the doctrine of "nascent stages" has come to be applied 
to the phenomena of mental development generally 



60 STANFORD REVISION OF BINET-SIMON SCALE 

and is now almost a dogma in the literature of child 
psychology. Researches are rapidly showing, how- 
ever, that instincts themselves have less a Minerva- 
birth than we had supposed, a fact which Freudian 
psychology has demonstrated in the case of the 
sex instincts. As far as general intelligence is con- 
cerned, there is little evidence of periodicity or irregu- 
larity. If such periodicity or irregularity occurred, 
the intelligence quotient of the developing child 
would be now high, now low, instead of maintaining 
a fairly constant value. ^ 

The facts we have presented offer little hope to the 
parent who would like to believe that his backward 
boy who is 6 or 8 years old will '^ catch up" in the 
supposed spurt of adolescence. Indeed, the much- 
talked-of adolescent spurt begins to look like a myth. 

These same facts, however, furnish some consolation 
to the parents of a young genius. It has been the 
custom for teachers and even for some psychologists 
to inspire in them a dismal and uneasy fear that such 
a child is in danger of retrograde development. We 
hear of great men who in childhood were famous 
blockheads, and of genius children who became numb- 
skulls! Perhaps it would not be safe to assert that 
such cases do not occur, for logic teaches that uni- 
versal negatives are hard to establish. If they do 
occur, we may suppose that a concrete example will 
sometime come to light, vouched for by the necessary 
scientific proof. 

3 Baldwin has recently shown that physical growth also proceeds at 
a nearly uniform rate from 7 to 14 years of age, and that a child's 
physical status, as expressed in height and weight, maintains a fairly 
constant position, with reference to norms, from age 6 or 7 through 
adolescence. Bird T. Baldwin: Physical Growth and School Progress. 
Bull U. S. Bur. of Ed., 1914, No. 581. 



VALIDITY OF THE INTELLIGENCE QUOTIENT 61 

Summary 

1. Retardation or acceleration of any given number 
of years has no meaning apart from the age of the 
child, and the method of expressing intelligence status 
in absolute years only should be abandoned. 

2. The distribution of intelligence quotients for 
the separate years argues strongly in favor of the 
intelligence quotient as a valid method of expressing 
a child's development status, at least for the years 
5 to 14. 

3. Data are presented which indicate that the 
intelligence quotient of a child of any grade of intelli- 
gence remains fairly constant until well into the period 
of adolescence. Doubt is thrown upon the existence 
of the supposed ''nascent stages," the "adolescent 
spurt," and other popularly assumed irregularities 
of mental growth. 



CHAPTER IV 

Sex Differences 

Our revised scale has been constructed by massing 
the results from boys and girls, and our discussion 
of the distribution of intelligence in Chapter II took 
no account of sex differences. However, when we 
treat the intelligence quotients of the boys and girls 
separately, we find a somewhat constant, though rather 
slight superiority of the girls from Ages 5 to 13, with 
the exception of Age 10. At 14 years the boys appear 
to be about as superior to the girls as the girls were 
superior to the boys at 5. This is shown in Graph 24, 
which gives the median intelligence quotient for the 
boys and girls separately at each age from 5 to 14. 

Graphs 25-34 show the distribution of intelligence 
quotients for the sexes separately, when grouped in 
ranges of ten, 56-65, 66-75, 76-85, 86-95, etc. Be- 
cause of the small number of boys or girls in any one 
year, successive ages have been combined for the 
graphs, as 5-6, 7-8, 9-10, etc. 

If, now, we combine the intelligence quotients for 
all ages from 5 to 14, inclusive, we have Graphs 35 
and 36 for boys and for girls, respectively. 

Comparison of the sexes with regard to the range 
of intelligence quotient that includes the middle 50 
percent shows that half the boys He between 91-107 
and half the girls between 93 and 109. Table 11 
shows the frequency of some of the more extreme 
degrees of variation according to sex. 

62 



SEX DIFFERENCES 



63 



1.00 



.90 



.60 



,4-0 



.ZO 





r 


6 


7 


8 


3 


10 


II 


12 


13 


14- 


Soys 1.00 


.9S 


I.OI 


1.00 


.98 


m 


SG 


.97 


M 


IDO 


Girls 1 


04- 


1.05 


I.OZ 


I.OZ 


1.01 


t.03 


LOl 


,99 


S7 


.96 



Graph 24, Showing median intelligence quotients for boys and girls 
separately at each age, number of boys, 457; girls, 448. 



64 STANFORD REVISION OF BINET-SIMON SCALE 



^e-GS 6G-75 76-85 86-95 9Q-I05 /oe-llS IIG-IZS I2G-I55 136-1^5 
ri, in, ZZ'L 3G7, I83'L 9'J. ZS'U 

Graph 25. Distribution of intelligence quotients of 87 boys, ages 5 

and 6 combined. 



5G'G^ e&'7j5 76-85 86-S5 96-/05 i06-ii5 Ii6-i25 i26'i35 l3G'i4'5 
I'l, 5% 14-V. 3G'/, Z3'/. I^y. 67. l7. 

Graph 26. Distribution of intelligence quotients of 87 girls, ages 5 

and 6 combined . 



SEX DIFFERENCES 



65 



c 



56-65 66-75 7S'85 SG-95 9e-/05 106-//5 JJG'/25 /26-J35/5G-l4'5 
1% /7o ^.57, 165% "hl'L Z37. lOV. Z'U ''U 

Graph 27. Distribution of intelligence quotients of 100 boys, ages 

7 and 8 combined. 



56-85 66-75 76-35 86-95 96-105 106-115 II6-/Z5 /26-135138'l'^S 
ru 7'U 19% 3J'L Z^'i. iZ'h "h'A 



Graph 28. Distribution of intelligence quotients of 91 girls, ages 7 

and 8 combined. 



66 STANFORD REVISION OF BINET-SIMON SCALE 



56-65 66-75 76-85 86-95 96-/05 i06-li5 ii6-iZ5 i2G-i35 i36-l^3 
65% 207, ^I'Jo Z^°/o S7o /'/. 

Graph 29. Distribution of intelligence quotients of 92 boys, ages 9 

and 10 combined. 



56-65 66-75 76-85 86-S5 38-/05 /06-//5 /I6-/25 /26-/35 /56-/4-5 
^% 857. /9.5% 3/5;. ZG^ $7. / 7, 2 7, 

Graph 30. Distribution of intelligence quotients of 108 girls, ages 

9 and 10 combined. 



SEX DIFFERENCES 



67 



56-65 £6-73 76-85 8S-9S 96-/03 106-/15 llG-125 l2Q-i35 I3Q-I^5 
1.5°/. 3% /3'/. 2f/. 2^1. Z0% 81 37, 

Graph 31. Distribution of intelligence quotients of 74 boys, ages 

11 and 12 combined. 



5G-G5 Q6-75 TGS^ 88-95 96-/05 106-1/5 116-/25 126-12)5 /3Q-/^5 
Zy. 9V, 171 32% 2^7. /2 5% Z'A /% 

Graph 32. Distribution of intelligence quotients of 88 girls, ages 

11 and 12 combiaed. 



68 STANFORD REVISION OF BINET-SIMON SCALE 



Se -G5 66' 7S 76 SS 36 -95 96- 105 106 -115 1/6 -125 J 26 ■ 135 /36 -/4-5 
2y, 6"/. /fV. ZO'I, 32'/. ZZ'/, 5'/. 

Graph 33. Distribution of intelligence quotients of 106 boys, ages 

13 and 14 combined. 



X 



56-G5 &e-75 76-86 86-9S 96-/05 /06-//S //6-I25 /Z6-/35I5G-I^5 
5.5'/. 87. 271 35'/. 17.51. S.51. 1.5'/. 

Graph 34. Distribution of intelligence quotients of 74 girls, ages 

13 and 14 combined. 



SEX DIFFERENCES 



69 



.S6 -es 66 - 75 76 -8S 86 -95' 36 -/OS 106 -IIS 116-125 l26'/3S/36'f4'S 

.i3% Z.t7t I0.£7'/. 2/J57, J3P57. ZZPl S.OGl 2J7t 

Gbaph 35. Distribution of intelligence'^quotients of 457 boys, 5-14 

years of age. 



^6-65 66-75 76-85 86-95 96-105 /06-1 15 II6-/Z5 IZ6-J35 J36-/^S 
.S2l 2077. 6f7'l. (8B71 JJ.7Z 2f.33l lOMl ZfS'L /J/7 

Graph 36. Distribution of intelligence quotients of 448 girls, 6-14 

years of age. 



70 



STANFOKD KEVISION OF BINET-SIMON SCALE 



TABLE 11 

Distribution of Certain Intelligence Quotients in 457 Boys and 448 

Girls 





Total 
60 or 
lower 


Total 
70 or 
lower 


Total 
75 or 
lower 


Total 
125 or 
higher 


Total 
130 or 
higher 


Total 
140 or 
higher 


Boys... 
Girls. . . 


No. 

1 
1 


% 
.21% 

.22% 


No. 
4 

5 


% 
.87% 

1.11% 


No. 
13 
14 


% 
2.83% 
3.12% 


No. 

11 

17 


% 
2.39% 

3.47% 


No. 

5 
8 


% 
1.08% 
1.74% 


No. 

3 


% 
.66% 



The facts we have presented indicate that, apart 
from a sUght superiority of the girls from 5 to 12 years, 
the distribution of intelligence is much the same for 
the sexes. There is no evidence of any wider range 
of intelligence among boys, such as has commonly 
been supposed to exist. The difference, if any exists, 
seems to be in the other direction. A slightly larger 
percent of girls than of boys falls to 75 or below, which 
is the point frequently taken as indicating feeble- 
mindedness, and a decidedly larger percent of girls 
reaches as high as 125. The range that includes the 
middle 50 percent is almost exactly the same in extent 
for the two sexes. This is all quite contrary to the 
traditional belief that both feeble-mindedness and 
exceptionally superior ability are more frequent with 
boys than with girls. ^ 

Although the superiority of the girls is not great in 
amount, it appears over a long enough period to 
suggest that it may represent a genuine difference 
and not some accidental condition of the experiment. 

^ In support of our results we are glad to cite the study of Mrs. Leta 
Hollingworth : ''The frequency of amentia as related to sex," The 
Medical Record, Oct. 25, 1913, which is an analysis of 1000 cases ex- 
amined in the New York Clearing House for Mental Defectives. See 
also, by the same author: ''Variabihty as related to sex differences 
in achievement, Am. J. Sociology, Jan., 1914, pp. 510-530; and the 
comparative variability of the sexes at birth, same Journal, Nov., 
1914, pp. 335-370. 



SEX DIFFERENCES 71 

It was first thought that part of the difference might 
be accounted for by the fact that two-thirds of the 
tests were made by women and only one-third by 
men, but when the inteUigence quotients were classi- 
fied according to the sex of the examiners no such 
influence was discovera,ble. There remains the possi- 
bility that the superiority of the girls in the tests 
may be the result of a somewhat more ready facility 
of the girls in the use of language, or of their greater 
willingness to respond. 

Fortunately the supplementary information fur- 
nished by the teachers affords us valuable data as 
to the genuineness of the sex difference in intelligence 
quotients. On page 48 was given the grouping of 
476 children, boys and girls together, according to 
tke teachers' estimates of intelligence. When these 
estimates are summarized for the boys and girls sep- 
arately (Table 12), the superiority of girls appears 
only in one respect: viz., 12, or 4.8 percent of the girls 
are classified in the ^Very superior'' group, as con- 
trasted with 3, or 1.3 percent of the boys. 

TABLE 12 

Teachees' Estimates of Intelligence for 229 Boys and 247 Girls, 

BY Sex 
Percent Very Very- 

Ranked Inferior Inferior Average Superior Superior 

229 Boys 3.9 14.4 56.7 23.5 1.3 

247Girls 3.2 13.7 57.0 21.0 4.8 

Table 12 is for the ages 5 to 14 combined. The 
teachers' estimates for the ages 13 and 14 were treated 
separately from the other ages in order to find out 
whether the tendency of the girls to lose their advan- 
tage in intelUgence quotient at this point is confirmed 
or contradicted by the judgment of the teachers. 
The results, shown in Table 13, bear out the tests, 



72 STANFORD REVISION OF BINET-SIMON SCALE 

for while the teachers have judged the inteUigence 

of the girls at earlier ages as fully equal, if not superior 

to that of the boys, they give the advantage at age 

13-14 to the boys. The table shows 19.5 percent 

of the boys of 13 and 14 years of age classed as below 

average, as contrasted with 24.5 percent of the girls; 

on the other hand, 26 percent of the boys are classed 

as above average, as contrasted with 13.5 percent of 

the girls. 

TABLE 13 

Teachers' Estimates of Intelligence of Boys and Girls for the 

Ages 5-12 and 13-14 
Percent Very Very- 
Ranked Inferior Inferior Average Superior Superior 
Ages 5-12 Boys 3.2 14.7 57.3 22.9 1.6 

Combined Girls 3.8 11.9 56.1 22.3 5.7 

Ages 13- Boys 6.5 13.0 54.3 26.0 0.0 

14 Combined.. Girls 0.0 24.5 62.0 13.5 0.0 

In like manner we have compared the boys and 
girls with reference to the quality of their school work, 
as judged by the teachers. When we classify the 
judgments for the ages 5-12 separately from those 
for 13-14, we have Table 14. 

TABLE 14 

Teachers' Estimates of the Quality of the School Work of 
Boys and Girls for the Ages 5-12 and 13-14 
Percent Very Very 

Kanked Inferior Inferior Average Superior Superior 

Ages Boys 3.8 11.1 60.0 23.8 1.1 

5-12 Girls 3.3 12.6 57.7 20.8 5.3 

Ages Boys 4.1 26.5 45.0 22.5 2.0 

13-14 Girls 2.4 19.5 53.6 22.0 2.4 

Table 14 agrees with the tests in showing a larger 
number of cases of greatly superior ability in school 
work among girls than among boys from 5 to 12 years. 
The data for Ages 13-14 agree with the tests less 
closely, for, while the boys are less inferior to the 



SEX DIFFERENCES 



73 



girls than in the ages 5-12, they are still somewhat 
inferior. 

There remains still another means of checking up 
the evidence of the tests as to the relative intelligence 
of boys and girls; we can compare their age-grade 
distribution in school. Fortunately, our data enable 
us to do this for all the children tested. Table 15 
gives the age-grade distribution for Ages 7 to 14. Ages 
5 and 6 are left out of account because children of 
this age have not had time to become retarded or 
accelerated in school, and those above 14 are eliminated 
because they represent a selected group — the '^ left- 
overs. '^ 

TABLE 15 

Age-Grade Distribution of Boys and of Girls for the Ages 7 to 

14. (In Percents) 



Age 


Grade 


I 


II 


III 


IV 


V 


VI 


VII 


VIII 


7 


Boys 

Girls 

Boys 

Girls 

Boys 

Girls 

Boys 

Girls 

Boys 

Girls 

Boys 

Girls 

Boys 

Girls 

Boys 

Girls 


77.7 
76.2 


22.3 
21.5 


2.5 

24.0 

18.2 


2.0 
2.5 

15.5 
14.0 


1.9 

3.5 

25.0 
16.4 


2.8 
2.0 

20.0 
35.2 




35.2 

2.7 
9.1 

27.7 
40.5 

13.3 
39.5 




8 


22.0 
27.0 

3.9 
5.2 


52.0 

52.5 




9 


32.8 
26.1 

2.8 
8.1 

5.3 



46.2 
50.8 




10 


25.0 
22.5 

8.4 
9.3 

13.3 


3.4 



44.4 
51.0 




11 


31.6 
16.4 

10.8 
9.1 

10.3 
2.6 

2.2 
3.0 


34.3 

37.2 


2.3 


12 
13 
14 


32.4 
32.0 

15.5 
5.4 

2.2 



40.6 
47.9 

38.0 
35.0 

24.5 
24.0 




2.5 

5.2 
16.2 

57.6 
33.Z 



74 STANFORD REVISION OF BINET-SIMON SCALE 

Inspection of Table 15 will show that the results 
lack uniformity. At Age 7 , the age-grade status 
of the girls is slightly better; at 8, the boys have a 
shade the advantage; at 9, the girls; at 10, the boys; 
at 11, 12 and 13, the girls are much in advance; while 
at 14, the boys are the first time decidedly ahead. 
On the whole, we may say that there is httle difference 
for Ages 7, 8, 9, and 10; that for the next three years 
the girls are much more advanced than the boys; 
and that at 14 the boys have much the advantage. 

Ignoring Year 7, since at this age pupils have had 
little time to become retarded or accelerated, we are 
justified in grouping the ages together as follows: 
Years 8, 9, and 10; years 11, 12, and 13; and finally, 
Year 14 by itself. Table 16 shows the percent of 
boys and girls retarded or accelerated 1, 2, 3, or 4 
years in each of these age-groups. 



TABLE 16 

Percent of Boys and Girls Retarded or Accelerated in School 

BY 1, 2, 3, OR 4 Grades in Various Age-groups 



Age 


Sex 


— i 


—3 


—2 


—1 


Normal 


+ 1 


+ 2 


+3 


+ 4 


Ages 

.8, 9, 10 

combined 


Boys. . . 
Girls. . . 






1.4 
4.6 


27.0 

25.3 


48.1 
51.3 


21.1 
16.0 


2.1 
2.6 






Ages 
11, 12, 13 
combined 


Boys. . . 
Girls. . . 


1.5 


10.0 

.8 


12.3 
8.0 


34.6 

27.5 


33.0 
42.0 


8.5 
20.1 


1.6 






Age 
14 


Boys. . . 
Girls. . . 


2.2 
3.2, 


2.2 


24.5 
24.2 


13.3 
39.3 


57.8 
33.3 











SEX DIFFEEENCES 



75 



TABLE 17 



Percent of Boys and Girls Retarded or Accelerated in School 
BY 1, 2, 3, OR 4 Grades, for the Ages 8 to 14 Combined 




—4 


—3 


—2 


—1 


Normal 


+ 1 


+ 2 


+ 3 


+ 4 


Boys 


.95 


4.47 


9.58 


28.11 


43.13 


12.77 


.95 






Girls 


.32 


.32 


8.11 


27.59 


45.45 


15.90 


1.94 


.32 





Table 17 shows the percent of boys and girls retarded 
or accelerated 1, 2, 3, or 4 years for all the ages 8-14 
combined. It should be emphasized, however, that 
the facts we want to know are best disclosed in Table 
16, and that the evidence goes to show that the grade 
progress of our hoys and girls differs little up to, and 
including Age 10, that for the next three years the girls 
are clearly in- advance, and that the reverse is the case at 
1/f.. In the main, therefore, the school progress of our 
subjects agrees with the intelligence tests, with the teachers' 
estimates of intelligence, and with the teachers' judgments 
of the quality of the school work, in showing a sex differ- 
ence which is in favor of the girls before 14, ctnd in favor 
of the boys thereafter. 

Before accepting this conclusion there is one other 
factor to be taken into account which might help to 
explain the apparent superiority of the boys at Age 14. 
A certain amount of selection has taken place in this 
age-group. A considerable number of the 14-year-olds 
have been promoted to the high school, and these are 
not included in our group of subjects of this age. This 
has doubtless occurred more often with the girls than 
the boys, for we have already showed that marked 
school acceleration occurs much oftener with girls 
than with boys at the ages 12 and 13 years. At Age 



76 STANFORD EEVISION OF BINET-SIMON SCALE 

12 there are 9.1 percent of the gMs in Grade VII and 
2.5 percent in Grade VIII, as compared with only 
2.7 percent of the boys in Grade VII and none at all 
in Grade VIII. Similarly, at Age 13 there are 16.2 
percent of the girls in Grade VIII as compared with 
only 5.2 percent of the boys. If all our 13-year-olds 
in Grade VIII should be promoted to the high school 
at the end of the year, the number of 13-year-old girls 
receiving such promotion would accordingly be more 
than three times as great as the number of boys. If 
this situation holds true generally, it can not be safely 
ignored in making a comparative study of the intelli- 
gence of boys and girls at the age of 14. Even at 13, 
unequal selection appears to have taken place to no 
small degree, as would appear from the following 
age-grade distribution (in percent s) of 13-year-old 
boys and girls: 

TABLE 18 





III 


IV 


V 


VI 


VII 


VIII 


13 Boys.... 


. 3.4 


10.3 


15.5 


38 


27.7 


5.2 


year 

olds Girls 




2.6 


5.4 


35 


40.5 


16.2 



The foregoing distribution would suggest that our 
13-year-old boys are almost free from any selection 
as far as pro motion to the high school is concerned, 
but that probably 5 percent or more of the girls who 
ought to be present at this age are not in our group. 
Comparison of the relative number of boys and girls 
tested at different ages fuUy confirms this suspicion. 
Table 19 shows that, while the number of girls found 
in the grades equals or exceeds the number of boys 
at every age but one below 13, yet at 13 and 14 the 
girls make up only about 41 percent of the entire 
number. This is significant when it is remembered 
that, in all the schools where testing was done, all 



SEX DIFFERENCES 77 

the boys and girls below the high school were tested 
who were within two months of a birthday, whatever 
grade they may have been in. By the laws of chance 
the number of boys and girls found at each age ought 
to have been nearly equal, barring selective influences. 

TABLE 19 

Percent the Girls Form op the Entire Number of Pupils in 
Grades Below the High School at Each Age 

Age 5 6 7 8 9 10 11 12 13 14 15 16 

Percent... 50 50 49.5 46 51.3 57.5 56 53 41 41.5 45 28.6 

The only possible conclusion seems to he that the 
apparent superiority of hoys at the age of 14-, as well as 
also their diminished inferiority at 13, is due solely to 
the unequal selection which has taken place at these ages. 
The results of the tests themselves, the teachers' 
estimates of intelligence, the teachers' judgments 
about the quality of school work, and the age-grade 
distribution, offer four separate and distinct lines of 
evidence pointing in this direction. The same four 
lines of inquiry are also in general agreement in show- 
ing a distinct, though slight superiority of the girls 
in the ages below 13. 

Unfortunately, most of the studies made with the 
Binet tests throw little light on sex differences. In 
only two studies besides our own have the subjects 
tested been nearly enough non-selected to make such 
a comparison worth while, namely, in Goddard's 
tests of 1500 Vineland school children and in Kuhl- 
mann's tests of 1000 Faribault school children. Kuhl- 
mann, however, has not analyzed his data for the 
sexes separately, and Goddard has done so only to 
the extent of giving the percent of boys and girls 
testing 1, 2, 3, 4, or more years above or below age. 



78 STANFORD REVISION OF BINET-SIMON SCALE 

Even this is given by Goddard only for all the ages 
taken together, a procedure which ignores the unequal 
significance of a given number of years of retardation 
with children of different ages. However, his data 
for the ages combined agree with our own in indicating 
a slight superiority of the girls. 

TABLE 20 

Sex Differences as Shown by the Binet Tests (Goddard) 

— 2 years — 1 year At age +1 5 ear +2 years 

Percents or more or more or more 

Boys 18.5 23 34.5 20 4 

Girls 18.5 17 36.5 23 5 

Bloch and Preiss made comparisons for sex differ- 
ences in their tests of 79 boys and 71 girls aged 7 to 
11 years. However, their results, which indicated a 
marked superiority of the boys, throw no light on the 
question of real sex differences, for the reason that 
their subjects had been selected from a large number 
as being supposedly "average'^ in intelUgence, and we 
have no means of checking up the effect of this selec- 
tion. 

The only other Binet results thus far published 
which may be used for comparative purposes are those 
of Yerkes and Bridges, who present the sex differences 
found in the use of their Point Scale with 760 grammar 
school children from the kindergarten to the eighth 
grade. The school chosen was located in a ^ ^medium 
to poor'^ district, but otherwise there seems to have 
been no selection of subjects which could have influ- 
enced sex differences except the fact that in this study, 
as in our own, the 14 and 15-year-olds tested were 
composed wholly of those who had not progressed 
in school beyond the eighth grade. 

To make comparison easier, Yerkes' and Bridges' 
curves showing the average scores earned by boys 



SEX DIFFEEENCES 79 

and girls of different ages are reproduced here. We 
have chosen the curves obtained by excluding the 
children of non-English-speaking parents. When the 
latter were included, the curves crossed and re-crossed 
so often as to have no clear significance. 

It will be noted that the results of Yerkes and Bridges 
are not altogether in harmony with our own. The 
two scales agree in that both show a superiority of 
the girls in the earlier ages and a superiority of the 
boys at Ages 14-15. The latter, in all probability, 
has the same cause in both cases, namely, the more 
frequent elimination of 13, 14, and 15-year-old girls 
from the grades by promotion. Yerkes and Bridges, 
however, seem not to have considered this possibility. 
In the middle ages the results of the two studies are 
quite in contrast. 

In evaluating these somewhat contradictory find- 
ings it should be remembered, (1) that the Stanford 
data are based on more than twice as many children 
as those entering into the Yerkes-Bridges curve; (2) 
that all of our children were within two months of a 
birthday, thus obviating large possible errors likely 
to result from dividing a small number of children 
with age differences ranging up to one year into sex 
groups; and (3) that the number of tests in the Stan- 
ford revision is much larger than that included in the 
Yerkes-Bridges scale, thus reducing the part played 
by chance. 

In conclusion, we may say that the evidence seems 
to us to point to the existence of a small sex difference 
in intelligence, which, but for the influence of selection, 
would probably be in favor of the girls at all ages from 
5 to 13 or 14 at least. It should be emphasized, how- 
ever, that the difference is small, amounting to no 



80 STANFORD REVISION OF BINET-SIMON SCALE 



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4- S 6 7 8 9 JO // /Z 13 14- /S- 

Average Scores Earned by 468 Boys and Girls of Different 
Ages with the Yerkes-Bridges Point Scale 



SEX DIFFERENCES 81 

more than 6 percent in terms of intelligence quotient 
at any age, and at most ages from only 2 percent to 
4 percent. In view of the wide distribution of intelli- 
gence in each sex (from 50 to 150 intelligence quotient), 
a difference of 2-4 percent in median intelligence 
would be practically negligible, even if it were dem- 
onstrably genuine. The difference actually found is 
so small that it might conceivably result from a sex 
difference in temperamental traits having nothing 
to do with intelligence, such, for example, as a differ- 
ence in willingness to attempt a novel task, difference 
in timidity, or what not. We prefer not to indulge 
in speculation. At any rate we find no reason to 
share the opinion voiced by Yerkes and Bridges ^^that 
at certain ages serious injustice will be done to individ- 
uals by evaluating their scores in the light of norms 
which do not take account of sex differences." 

Finally, the individual tests were examined sep- 
arately for sex differences. Since the number of our 
pupils of one sex was ordinarily not larger than 40 to 
50 at one age, it was found that the increase in the 
percent passing in successive years was so irregular 
as to be very confusing. One way out of this difficulty 
is to mass together the percents of boys (or girls) 
passing a test at three separate age levels: the age 
at which the test appears in the scale, and the adjoining 
ages above and below. We have not deemed a sex 
difference worth noting unless it appeared in all of 
these three successive age levels and to such an extent 
that the superiority averaged 10 percent for the three 
ages taken together. This is, of course, an arbitrary 
basis, but some such plan is necessary to escape the 
confusion and contradiction engendered by chance 
variations due to small numbers. As will be seen 



82 STANFORD REVISION OF BINET-SIMON SCALE 



from Table 21, the number of tests in which significant 
sex differences appear, is not large — orly 19 out of 58.» 

TABLE 21 

Sex Differences in Individual Tests 



SuPEiiioEiTY OF Boys 


Superiority of Girls 


Tests ia which the super- 
iority of Boys in three 
successive years averaged 
10 percent or more 


Amoiint 

of such 

superiority 

in 

percent 


Tests in which the super- 
iority of GmLS in three 
successive years averaged 
10 percent or more 


Amount 

of such 

superiority 

ia 

percent 


Arithmetical reasoning, 

XIV 
President and king, XIV 
Form-board, IX 
Fables, XII 
Making change, IX 
Hands of clock, XIV 
BaU and field, XII 
Similarities, XII 
[nduction, XIV 


33 
25 
20 
15 
15 
12 
11 
11 
10 


Designs from memory, X 
Aesthetic compr., V 
Ball and field, VIII 
Giving differences, VII 
Comprehension, VIII 
4 digits backwards, IX 

6 digits, X 

7 digits, XIV 
Bow-knot, VII 
Rhymes, IX 


19 
17 
16 
13 
12 
11 
10 
10 
10 
10 



Smaller differences were found in favor of the boys 
in Copying a Diamond (VII), Giving Easy Similarities 
(VIII), Naming the Months (VIII), and Defining 
Abstract Words (XII) ; in favor of the girls in Repeat- 
ing 5 Digits (VII), Naming the Days of the Week 
(VII) and Hard Comprehension (XII). 

We refrain from extended comment on the list 
of tests in which sex differences have been found. 
It will probably agree badly enough with anyone's 
a priori expectations. There are apparent contra- 
dictions, also, as well as surprises. We have no theory 



2 The tests of Years 3 and 4, and those of the "average adult" and 
"superior adult" were left out of this comparison because of insufficient 
data. 



SEX DIFFERENCES 83 

to explain why the girls are superior on the ball and 
field test of Year VIII (score 2) and the boys on the 
same test at Year XII (score 3); or why the boys 
are better in the tests of giving similarities, and the 
girls in the test of giving differences. Perhaps we 
should have expected the superiority of the boys in 
arithmetical reasoning, the form-board, and making 
change; likewise the superiority of the girls in aesthetic 
comparison, tying a bow-knot, and repeating digits. 

Summary 

1. The tests indicate a slight superiority of girls 
over boys at each age from 5 to 13. The apparent 
superiority of the boys at 14, however, is probably 
accounted for by the unequal selection which has taken 
place in the promotion of pupils to the high school. 

2. The small superiority of the girls in the tests 
probably rests upon a real superiority in intelligence, 
age for age. At least, this conclusion is supported 
by the age-grade distribution of the sexes, and by 
the teachers^ rankings according to intelligence and 
quality of school work. 

3. Apart from the small superiority of the girls, 
the distribution of intelligence shows no significant 
difference in the sexes. The data offer no support 
to the wide-spread belief that girls group themselves 
more closely about the median or that extremes of 
intelligence are more common among boys. 

4. Not many of the individual tests show large 
sex differences in the percent passing in three con- 
secutive years. In certain of the tests, however, 
the differences were marked and unexpected. 



CHAPTER V 

THE RELATION OF INTELLIGENCE TO 
SOCIAL STATUS 

In the use of the Binet scale with different social 
classes it has generally been found that children who 
come from superior environment test higher than those 
who come from homes where the degree of culture 
is inferior. As already noted, the arrangement of 
tests in the 1908 Binet scale was based on an exami- 
nation of about 200 children from one of the poorest 
quarters of Paris. WTien the scale thus derived was 
used by Decroly and Degand in the examination of 
children from wealthy and cultured homes, in a Brus- 
sels private school, it was found that many of the 
tests were passed two years below the location assigned 
them by Binet. Jeronutti's tests of 144 better-class 
children of Rome agree closely with those of Decroly 
and Degand. The same is true of Madame Wolk- 
owitsch's tests of private-school children at Petrograd. 
On the other hand. Dr. Anna Schubert's data gathered 
from 229 lower-class children in a Moscow orphanage 
gave a distribution of mental ages skewed in the 
opposite direction. In fact, none of Dr. Schubert's 
children were advanced more than one year, only 
27 percent tested '^at age," while 75 percent were 
retarded one j^ear or more and 39 percent two years 
or more. 

Binet, himself, took up the question by having 
tests made of 54 children who had been classified into 
four groups by the teachers according to social status. 
Unfortunately, the school chosen was one which was 

84 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 85 

not attended by children of the highest social classes, 
and the number tested was very small. The results 
failed to show any correlation of mental age with 
social status. A later comparison by Binet of 30 
children attending a poorly situated school with 30 
others attending a school in a well-to-do neighborhood 
of Paris showed a marked difference in favor of the 
better situated children. 

The Breslau experiment, of which a partial account 
has been given by Stern, ^ indicated that pupils of 
the Volksschule are at the age of 10 years somewhere 
near the level of mental development which is at- 
tained by pupils of the Vorschule at 9 years. The 
Volksschulen are attended mainly by children of the 
laboring and lower business classes and the Vorschulen 
by children of the better classes. Likewise, in com- 
paring children of the upper and lower social classes 
in English infant schools, Winch found the children 
of the higher class superior to the other group in a 
majority of the tests. 

Study of the data which we have collated for the 
individual tests of the scale shows that large differ- 
ences found by investigators in the percentage of 
children who pass certain tests may often be accounted 
for by a difference in the social class of the subjects. 

Yerkes and Bridges compared 54 pupils of a better- 
class school with an equal number attending a poor 
school. The sexes were represented equally, and the 
pupils were selected in such a way that a boy or girl 
of the favored group was matched by a boy or girl 
of approximately the same age from the unfavored 
group. The comparison showed that by the Yerkes- 

^ The Psychological Methods of Testing Intelligence, These Mono- 
graphs, No. 13, 1914, pp. 54 fiF. 



86 STANFORD REVISION OF BINET-SIMON SCALE 

Bridges scale the favored boys averaged 7.7 points 
higher and the girls 8.4 points higher than did the 
members of the unfavored group of the same ages. 
If we compare this difference in points with the age- 
norms given by Yerkes and Bridges, we find that it 
represents about a year of difference in mental ad- 
vancement with children of this age. Binet at one 
time estimated that social status might make as much 
as a year and a-half difference in mental age, though 
in making this statement he seems to have overlooked 
the fact that a retardation of a year and a-half is not 
of equal significance in the lower and upper ages. 

The tacit assumption which most writers seem to 
have made in their discussions of such facts as those 
we have just set forth is that the difference found is 
due wholly, or at least mainly, to the influence of 
environment. Meumann believes that the most seri- 
ous fault of the Binet scale is its failure to take account 
of the influence of social environment on the ability 
to pass certain tests. Yerkes and Bridges assert 
that ''it is obviously unfair to judge by the same norm 
of intelligence two children, the one of whom comes 
from an excellent home and neighborhood, the other 
from a medium-to-poor home and neighborhood.'' 

As will be shown presently, we believe that the 
facts may be more reasonably explained on an entirely 
different h^^^othesis. First, however, we will set 
forth somewhat in detail the Stanford data that bear 
upon this question. 

As stated elsewhere, we were able to secure a classi- 
fication of 492 of our children according to social 
class into five groups: 'Very inferior," "inferior," 
"average," "superior" and very superior." Although 
the schools chosen for the tests were on the whole 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 87 

as nearly average as could be found, it will be readily 
understood by anyone who is acquainted with the 
democracy of the American educational system that 
in almost any small city an ' 'average" school contains 
some children of every social class. As was expected, 
therefore, all the social classes were found to be rep- 
resented in every school. Graph 38 shows the dis- 
tribution by social class of the 492 children regarding 
whom the supplementary information was obtained. 




l/fir/ Inferior /riferior Ai/trac/e Superior \/ery Superior 

27. IBBI 5G.51 20BV. I^y. 

Graph 38. The Distribution by Social Class of 492 Children 

OF All Ages. 

We have next classified these same pupils according 
to the intelligence quotients resulting from the tests, 
and for this purpose also we have made use of five 
groups, as follows: 

I Q 120 or 

1 Q below 80 I Q 80-89 I Q 90-109 I Q 110-119 above 

"Very infe- "Very 

rior" "Inferior" "Average" "Superior" superior" 



88 STANFORD REVISION OF BINET-SIMON SCALE 

This grouping of the inteUigence quotients is, of 
course, arbitrary, but some sort of grouping is neces- 
sary, and the one we have employed has the advantage 
of giving five groups of inteUigence quotients which 
agree roughly in size with the groups according to 
social class. This correspondence is as follows: 

TABLE 22 
Percent op Pupils in Each Group 

I Q I Q below 80 1 Q 80-89 I Q 90-109 I Q 1 10-119 I Q 120 or above 

6.9 14.5 57.7 15 5.6 



Social 


Very 








Very 


Status 


inferior 


Inferior 


Average 


Superior 


superior 




2 


16.6 


56.5 


20.6 


1.6 



Table 23 shows where the children in each social 
group fall with reference to intelligence quotient, and 
also where those of any intelligence quotient group 
fall with reference to social class. 

TABLE 23 
The Relation of Intelligence to Social Status 









I Q 








Social 










120 or 




Status 


Below 80 


81-89 


90-109 


110-119 


above 


Total 


Very 
Inferior 


4 


4 


3 








11 


Inferior 


18 


15 


43 


4 





102 


Average 


9 


43 


181 


48 


11 


292 


Superior 


1 


7 


59 


21 


14 


80 


Very 
Superior 








3 


2 


2 


7 


Total 


32 


69 


289 


75 


27 


492 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 89 

That there is a certain degree of correlation between 
intelligence quotient and social status is quite evident 
from a glance at the table. Of the 27 children with an 
intelligence quotient of 120 or above, not a single 
one comes from a social class below the average; of 
the 75 with an intelligence quotient between 110 and 
119, only 4 belong to the "inferior'' social group, and 
none to the "very inferior group." Conversely, of 
the 32 children with an intelligence quotient below 80, 
only one is classified below the "average" social group. 
Only the middle intelligence quotient group, 90-109, 
is represented in all the social classes; and only the 
"average" and "superior" social group is represented 
in all the intelligence quotient groups. Application 
of the Pearson formula to the data in this table gives 
a correlation of .40 between social status and intelli- 
gence quotient. 

Another way to express the relationship between 
intelligence and social status is to compare the median 
intelhgence quotient for the children of each social 
group, as follows: 



Social Group Very Inferior Inferior 


Average 


Superior 


Very Superior 


Median I Q 85 93 


99.5 


107 


106 



Since only 8 pupils are included in the "very in- 
ferior" and only 10 in the "very superior" social 
groups, the medians for these extreme groups have 
limited significance. The case is different, however, 
in the "inferior," "average" and "superior" groups, 
which include 80, 292, and 102 cases, respectively. 

Graphs 39, 40, and 41 show the distribution of 
intelligence quotients grouped by lO's for the three 
social classes. In this case the 7 "very inferior" 
pupils are thrown with the "inferior" class, and the 
11 "very superior" pupils with the "superior" class. 



90 STANFORD REVISION OF BINET-SIMON SCALE 



SG - 65 66 - 7S 7<S -8S <96 -55* 3& '105 I Ob -US JIG -125 IZ 6 -155 /J6 V^j 
^ j.a% <9.6% 255/. ^2^. ^i-X- Z6% 

cJl.DisVribuTion of / Qs of tOS children of "£ uptr/or' onc/''yert/ super/'or' 

AociqI clQfise.^,. 



























1 7= 







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\tO,Ui^Tri'buT'iOti of I Q's of ZSS" chi/dren of " a-verajc'' socio/ clo&'i 



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^^j, Oi^'Tri buTi'on of I Qs oj 86 ch ( Idran of'iTifcr ('or a-nd ''\/trj^ inf trior* 

social classes. 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 91 

The median intelligence quotient of the ^'average'' 
social group is 99.5, and so practically coincides with 
the median for all classes taken together. It is sig- 
nificant that the median intelligence quotient of the 
^^inferior'' group is 14 points below that of the '^superior" 
group, and that the median intelligence quotient for the 
^^average^' group lies approximately mid-way between 
the two. The difference between the median intelli- 
gence quotients of the ''inferior'^ and the '^superior" 
groups means a difference in mental age at the various 
actual ages as follows: 

TABLE 24 
Median Diffekence in Mental Age 



Age 




Age 




4 


6.7 mo. 


10 


16.8 mo 


5 


8.4 " 


11 


18.5 " 


6 


10.1 " 


12 


20.2 " 


7 


11.7 " 


13 


21.8 " 


8 


13.4 " 


14 


23.5 " 


9 


15.1 " 


15 


25.2 " 



Our results, accordingly, agree closely with those 
of other workers. Our next task is to find the most 
rational hypothesis which will explain the correlation 
between social status and intelligence quotient. 

The usual assumption has been that the correlation 
is the artificial product of environmental influences; 
that the child from a cultured home does better in the 
tests by reason of his superior home training and because 
he has had more opportunity to pick up the informa- 
tion which success in the various tests calls for. This 
explanation has seemed to us from the beginning a 
most improbable one. Several investigations of the 
influence of environment on mental traits suggest 
the conclusion that this influence is much less important 
than is original endowment in determining the nature 



92 STANFORD REVISION OF BINET-SIMON SCALE 

of the traits in question. From an a-priori stand- 
point, the endowment hypothesis explains the correla- 
tion between intelligence quotient and social status 
just as adequately as does the environment hypothesis. 
To conclude, as Meumann and Yerkes have done, 
that the demonstration of the existence of such a 
correlation invahdates the Binet scale as a method 
of measuring intelhgence is to make a gratuitous 
assumption — an assumption, indeed, which is con- 
tradicted by much evidence from investigations bearing 
on the mental endowment of different social groups. 
We have thought it worth while, therefore, to sift 
our data somewhat carefully for evidence on this 
point. 

First, we have compared the social status of the 
children with the teachers' estimates of intelligence. 
The tests themselves are brief. Success in some of 
them, it must be admitted, hinges upon information, 
the possession of which might conceivably be largely 
conditioned by home environment. One thinks in 
this connection of such tests as naming coins, making 
change, repeating the days of the week and the month 
of the year, giving definitions, giving the moral of 
fables, etc. Success in certain others would appear 
to depend rather too much on facility in the use of 
language. But the teacher's judgment as to a child's 
intelligence is based upon months of acquaintance, in 
this case from half to an entire school year. The 
teacher has had abundant opportunity to distinguish 
between real mental ability on the one hand and the 
accidents of knowledge, or facility in the use of langu- 
age, on the other. Accordingly, Table 25, which 
gives the teacher's judgment as to the intelligence of 
each child in the various social groups, should be of 
interest. 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 93 

TABLE 25 

The Intelligence op Children op Various Social Classes as 
Estimated by the Teachers 







Teachers' Estimate of Intelligence 




Social 


Very- 








Very- 




Status 


Inferior 


Inferior 


Average 


Superior 


Superior 


Total 


Very 
Inferior 


6 


2 


3 








11 


Inferior 


4 


31 


36 


5 


1 


77 


Average 


7 


34 


93 


50 


4 


188 


Superior 


1 





40 


56 


4 


101 


Very- 
Superior 











2 


6 


8 


Total 


18 


67 


172 


113 


15 


385 



Casual inspection of this table shows that the judg- 
ment of the teachers accords with the evidence from 
the tests in crediting greater mental ability to the 
children of superior social status. Not one of the 
children of the 'Very superior^' social group is ranked 
below '^superior" intelligence, and of the 101 included 
in the "superior'' social group only one falls below 
"average" intelligence. Conversely, not one of the 
11 children of "very inferior" social status ranks above 
"average" in intelligence, while 6 of them are classified 
as intellectually "very inferior." By the Pearson 
formula the correlation between social status and the 
teachers' estimates of intelligence is .55. This is 
considerably higher than the .40 correlation found 
between social status and intelligence quotient. 

But children from superior homes are likely to be 
better dressed, cleaner and more attractive in appear- 
ance than children from the poorer homes. Perhaps, 



94 STANFORD REVISION OF BINET-SIMON SCALE 

too, they are better behaved, more responsive, and 
socially more adaptable on account of superior training 
in the home. It is conceivable that external appear- 
ances of this kind, which, all would agree, are in part 
an expression of home conditions, have deceived the 
teachers and influenced their ranking of the children 
according to intelligence. 

If this were true, the actual quality of the school 
work done by the children of various social groups 
might be expected to afford a corrective for this possible 
error. School work, because it is more definite and 
objective, is easier to judge than the complex of mental 
traits called intelligence. Table 26 shows the quality 
of the school work, as judged by the teachers, for all 
the children of the several social groups. 

TABLE 26 

The Quality of School Work Done by Children of the Various 

Social Groups 







Quality of 


School Work 




Social 

Status 


Very 
Inferior 


Inferior 


Average 


Superior 


Very- 
Superior 


Total 


Very 
Inferior 


5 


4 


3 








12 


Inferior 


10 


29 


35 


6 


2 


82 


Average 


9 


52 


160 


60 


4 


285 


Superior 





4 


51 


46 


4 


105 


Very- 
Superior 











2 


6 


8 


Total 


24 


89 


249 


114 


16 


492 



By the Pearson formula the correlation expressed 
in this table amounts to .47, which is only a little 
lower than that found for the teachers' estimates and 



EELATION OF INTELLIGENCE TO SOCIAL STATUS 95 

social status, and somewhat higher than that between 
social status and intelligence quotient. 

We would attach especial importance to this correla- 
tion, for the reason that the wide-spread use of peda- 
gogical tests in recent years has demonstrated that 
the individual differences in subject-proficiency which 
such tests bring to light among school children repre- 
sent, in large part, individual differences in native 
endowment and not the effects of unequal home or 
school training. Even spelling abihty, contrary to 
common opinion, is largely a function of general intelli- 
gence. As Mr. Houser has shown, the correlation 
between the two ranges from 35 to 71 percent. 2 In- 
dividual instruction, ^^ special class' ^ methods, indeed, 
the concentrated efforts of an entire school system, 
are unable to wipe out the major differences of this 
kind in a dozen years. As a rule, the longer the child 
is in school, the more evident the inferiority of the 
inferior child becomes. It would hardly be reason- 
able, therefore, to expect that a little incidental experi- 
ence and instruction in the home, amounting perhaps 
in most cases to not more than a few minutes per day, 
would weigh very heavily against these native differ- 
ences. Even in good homes, children are likely to 
learn less from their parents than from their play 
fellows and nurses. 

For further evidence on the relation of school success 
to social status, we will examine the age-grade dis- 
tribution of the children in the five social groups. 
This is shown in Table 27 for the ages 8-16. Children 
below 8 were omitted from this comparison because 

2 See J. D. Houser: ''The relation of ability to general intelligence 
and to meaning vocabulary. The Elementary School Journal, Dec, 
1915. 



96 STANFORD REVISION OF BINET-SIMON SCALE 



TABLE 27 
The Relation of Age-grade Distribution to Social Status 









Location in the 


Grades 


Social 
Status 


Retarded 


In 


Advanced 












Grade 










4 yr. 


3yr. 


2 yr. 


1 3-r. 


for Age 


1 yr. 2 yr. 


3 yr. 


Total 


Very 
Inferior 


1 


1 


2 


2 


2 








8 


Inferior 


3 


4 


10 


27 


11 


4 






59 


Average 


1 


4 


21 


66 


109 


21 


2 




224 


Superior 






4 


16 


30 


14 






64 


Very 
Superior 








3 


2 


1 






6 


Total 


5 


9 


2,1 


114 


154 


40 


2 




321 



they have not had time to become much retarded or 
accelerated in school. Normal progress is here defined 
as Grade II at Age 8, Grade III at Age 9, etc. 

The correlation here is positive, but somewhat 
smaller than in the case of the intelligence quotient, 
the teachers' estimates of intelligence, and the quality 
of the school work. This is what we should expect, 
knowing that the tendency of schools is to promote 
children by age rather than by quality of school work 
or native abihty. 

Again, if home environment really has any con- 
siderable effect upon the intelligence quotient we 
should expect this effect to become more marked, the 
longer the influence has continued. That is, the 
correlation of intelligence quotient with social status 
should increase with age. We have accordingly 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 97 

worked out the correlation between intelligence quo- 
tient and social status for three separate age-levels: 
for Years 5, 6, 7 and 8 taken together; for 9, 10, and 11 
combined; and for 12, 13, 14, and 15 likewise combined. 
The coefficients of correlation for these three age- 
levels were, respectively, .43, .41, and .29. In other 
words, the longer the supposed powerful influence of 
home environment is continued, the more independent 
of it the intelligence quotient becomes. The con- 
clusion indicated is that the home environment, as 
environment^ has in all ages of childhood relatively 
little weight in determining the intelligence quotient. 
One other line of argimaent remains. Anyone who 
has done much testing knows that if sufficiently large 
numbers are taken, every degree of intelligence from 
profound Idiocy to very superior ability is represented 
in every social class. This did not happen to be true 
in the case of our 500 non-selected children from whom 
supplementary data were available, but we may be 
certain that it would have been true if a hundred or a 
thousand times as many children had been tested. 
In miscellaneous testing, the data from which are 
not included in the present study of non-selected 
children, we have found two children of extraordinarily 
poor home environment who had an intelligence 
quotient of 150. The highest we have ever found 
among children of any class is 170. It is a coramon- 
place that dull and feeble-minded children of all grades 
of deficiency may be found in any social class. We 
have tested two feeble-minded children whose fathers 
were men of substantial reputation for scientific 
achievement. It goes without saying that in each 
case the home environment was everything that could 
have been desired. In each family there are other 



98 STANFORD REVISION OF BINET-SIMON SCALE 

children whose intelHgence quotients range from 115 
to 125. Three children were tested in another family, 
in which the home conditions were about as wretched 
as could be imagined. Two of these children had an 
intelligence quotient between 75 and 85, the third 
an intelligence quotient of 120. The two former have 
since shown their inability to do fifth-grade school 
work by the age of 15 years, while the latter entered 
the high school at the age of 12. Since the unfavorable 
home environment did not prevent the superior endow- 
ment of the one child from evidencing itself in the 
tests, we must conclude that the inferior showing 
of the other two could have not been caused by this 
same environment. 

These are individual cases, and we would not stress 
them unduly. They do illustrate, however, a most 
important fact, — that exceptionally superior endow- 
ment is discovered by the tests, however unfavorable 
the home from which it comes, and that inferior men- 
tality can not be overcome by all the advantages of 
the most cultured home. 

Of course, we would not deny all possibility of 
environmental conditions affecting the result of an 
intelligence test. On the contrary, we have no doubt 
that the influence, is always present in some degree. 
What it accounts for in terms of the intelligence 
quotient, we do not know. That it accounts for the 
larger and more significant differences seems to us 
wholly improbable. We have little reason to believe 
that ordinary differences in social environment (apart 
from heredity) — differences such as those obtaining 
between the higher and lower classes of children 
attending approximately the same general type of 
school in a civilized community — impair the validity 
of the scale to any great extent. 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 99 

A crucial experiment would be to take a large number 
of young children of the lower classes and, after placing 
them in the most favorable environment obtainable, 
to compare their later mental development with that 
of children born into the best homes. No such study, 
properly safe-guarded, seems to have been made. 
The study would be quite feasible if carried out with 
the cooperation of a well-conducted orphanage. Some 
of the tests which have been made in such institutions 
indicate that mental subnormality of both high and 
moderate grades is extremely frequent among children 
who are placed in these homes. Most, though ad- 
mittedly not all of them, are children of inferior social 
classes. 

Of 20 orphanage children tested by the writer only 3 
were fully normal. The other 17 ranged in intelligence 
quotient from 75 to 95. Nearly all of these children 
had been in the orphanage for from two to several 
years. The orphanage in question is a reasonably 
good one and affords an environment which is about 
as stimulating to normal mental development as 
average home life among the middle classes. The 
children live in the orphanage and attend an excellent 
public school in a California village. ^ 

After all, does not common observation teach us 
that, in the main, native qualities of intellect and 
character, rather than chance, determine the social 
class to which a family belongs? From what is already 
known about heredity should we not naturally expect 
to find the children of well-to-do, cultured, and success- 
ful parents better endowed than the children who have 
been reared in slums and poverty? An affirmative 



3 Additional data will be published shortly on the influence of orphan- 
age life on the intelligence quotient of children who have come from 
1 ow-grade homes. 



100 STANFOED REVISION OF BINET-SIMON SCALE 

answer to the above question is suggested by nearly- 
all the available scientific evidence. The suggestion 
urged by Meumann and also by Yerkes, that it is 
unfair to evaluate the intelligence of any child except 
in terms of the average intelligence of his own social 
class, is not warranted. It would be just as logical 
to insist that it is unfair to the dull or feeble-minded 
child to judge his intelligence with reference to standard 
intelUgence for the mentally normal. 

Finally, it should be pointed out that Meumann's 
strictmres on the Binet scale in this connection had 
their origin in certain discrepancies observed in the 
results of various investigators, which seemed to him 
attributable entirely to differences in the social status 
of the subjects tested. It can be shown, however, 
that the observed discrepancies may be largely ac- 
counted for in other ways. They may have resulted 
in part from failure to follow the same procedure in 
giving or scoring the tests. Experience in training 
a fairly large number of individuals in the correct 
use of the Binet method leads one to stress this factor 
as a possible source of large discrepancies in results. 
Moreover, closer inspection of the discrepancies shows 
that they are much smaller than Meumann seems to 
have estimated them. As a criterion of agreement 
between two workers he uses the relative percentages 
of children found to test '^at age," +1, +2, — 1, — 2, 
etc. In certain cases, this criterion has been mis- 
leading. It is well known that the original Binet 
scale was much too easy at the lower end and much 
too difficult at the upper. Accordingly, whether the 
mental ages found by a given worker turn out to be 
predominantly plus or predominantly minus depends 
largely on the age of the subjects. If these are yoimg, 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 101 

the mental ages, by the original Binet scale, will tend 
to run too high. If they have reached an age which 
demands the use of the upper tests, the resulting 
mental ages will be too low. Meumann instances 
the high mental ages found by Jeronutti in his tests 
of better-class children in Rome as evidence purely 
of the influence of milieu. However, an examination 
of Jeronutti' s table of results by ages reveals the fact 
that the excess of plus mental ages is present only 
in the years below 10. Above 10, the mental ages 
fall predominantly on the minus side. Meumann 
seems to have been similarly misled with reference 
to the high mental ages found by Madame Wolko- 
witsch at Petrograd. Since her children were of 
kindergarten age, we may be sure that their high 
mental ages resulted in part from the incorrectness 
of the scale at this point and only in part from the 
high social status of the children. On the other hand, 
Meumann instances the excess of minus mental ages 
found in Miss Johnston's tests as an example of the 
unfavorable influence of low social status on test 
performance. The fact is that Miss Johnston's excess 
of minus mental ages occurs most noticeably in the 
years above 9, where the scale is demonstrably too 
hard. Of her 7-year-olds, only 5 tested minus and 
24 at or above age. 

We would agree with Stern that the remarkable 
fact is not that minor discrepancies have appeared 
in the statistics of different workers, but that their 
results, gathered in France, England, Germany, Russia, 
Italy, Belgium and diverse parts of the United States, 
from different classes of children and by methods 
which have undoubtedly fallen short of the desired 
uniformity, should agree as closely as they do. 



102 STANFOED REVISION OF BINET-SIMON SCALE 

It is quite possible that some of the individual tests 
of the Binet scale are affected by accidents of environ- 
ment and training to an extent which largely invali- 
dates them as measures of intelligence. We do not 
know which tests are included in this class, but re- 
search will ultimately disclose their identity. Kuhl- 
mann has shown how unsafe it is to condemn a test 
off-hand as subject to this or that disturbing influence.* 
The classification of the tests in Meumann's three-fold 
test series (tests of maturity, tests of endowment, and 
tests of milieu) is based upon inspection, and has little 
value beyond the program of research which it sug- 
gests.^ 

To ascertain the extent to which a test is influenced, 
by environment, apart from endowment, is not easy. 
An attempt was made to analyze the Stanford data 
for evidence of this influence on the individual tests, 
but it was abandoned. Of the 80 to 120 children at 
each age from 10 to 15 were ordinarily found in each 
of the two social classes ^'inferior" and ^ ^superior.'' 
Such numbers are at best too small to have statistical 
value, and in this case the matter was further com- 
plicated by the presence of large differences due 
presumably to native endowment. To all appear- 
ances, the average child of any social class behaved 
in the tests like a child of any other class who had the 
same intelligence level. 



* F. Kuhlmann: The Binet-Simon tests in grading feeble-minded 
children, J, of Psycho- Asthenics, XVI, 1912, pp. 173-193. 

^ See Terman's review of Meumann on the Psychology of Endow- 
ment, J. of Psych.-Asthenics, 14: 1914-1915: pp. 75-94: 123-134: and 
187-199. 



RELATION OF INTELLIGENCE TO SOCIAL STATUS 103 

Summary 

1. The median intelligence quotient for children 
of the superior social class is about 7 points above, 
and that of the inferior social class about 7 points 
below the median intelligence quotient of the average 
social group. This means that by the age of 14, 
inferior-class children are about one year below, and 
superior-class children about one year above, the 
median mental age for all classes taken together. 

2. That the children of the superior social classes 
do better in the tests is almost certainly due primarily 
to superior original endowment. This conclusion is 
supported by five supplementary lines of evidence: 
(a) the teachers' rankings of the children according 
to intelligence, (6) the age-grade progress of the chil- 
dren, (c) the quality of the school work, (c?) the com- 
parison of older and younger children as regards the 
influence of social environment, (e) the study of 
individual cases of bright and dull children in the same 
family. 

3. In order to facilitate comparison, it is advisable 
to express the intelligence of children of all social 
classes in terms of the same objective scale of intelli- 
gence. This scale should be based on the median 
for all classes taken together. 

4. Meumann's criticism of the scale with reference 
to the influence of social environment on the test 
results was based on insufficient examination of the 
data, particularly on the failure to take account of the 
prevailing ages of the children tested in different 
investigations. 

5. In their responses to individual tests, our children 
of a given social class were not distinguishable from 
children of the same intelligence level in any other 
social class. 



CHAPTER VI 

The Relation of Intelligence to School Success 

The degree of school success offers a partial check 
on the accuracy of the intelligence scale. While we 
should not expect complete agreement between scholar- 
ship and the results of even a perfect test of intelligence, 
nevertheless a very marked disagreement between 
the two would suggest some fault either in the tests 
or in the method of estimating school success. 

There are three main indices of the degree of school 
success which a given child has attained: (1) his 
advancement in the school grades, (2) the quality 
of school work he is doing in the grade where he is 
enrolled, and (3) the extent to which he is regarded 
by the teacher as intelligent. 

At first thought the last point may seem irrelevant. 
We are taking the term ^'school success," however, 
in an inclusive sense. In estimating an individual's 
success in life we ordinarily take into account not only 
the objective record of his achievements, but also the 
impression he has made on his associates and superiors. 
The latter is a real part of his success. For our present 
purpose it is important to know whether a child whose 
intelligence is judged by the teacher to be ^ ^inferior'' 
is really capable of doing ^ ^superior" school work; 
or conversely, whether a child judged by the teacher 
as of '^superior" intelHgence is likely to do "inferior' ' 
school work. 

104 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 105 



Comparison of Intelligence Quotient with the Quality of 

the School Work as Judged by 

the Teachers 

Table 28 shows the teachers' judgments as to the 
quahty of school work done by children of the intelli- 
gence quotient groups below 80, 80-89, 90-109, 110- 
119, and 120 or above. 

TABLE 28 

The Relation Between Intelligence Quotient and Quality of 
School Work (as Judged by the Teachers) 



Quality of 


Intelligence quotients 


School Work 
















Below 80 


89-89 


90-109 


110-119 


120-above 


Total 


Very 
Inferior 


12 


5 


8 








25 


Inferior 


9 


28 


49 


6 





92 


Average 


8 


34 


173 


32 


10 


257 


Superior 


1 


5 


60 


32 


15 


113 


Very 
Superior 








12 


3 


2 


17 


Total 


30 


72 


302 


73 


27 


504 



It is evident from the table that a fairly high correla- 
tion is present. No child doing ^ Very superior' ' school 
work has an intelligence quotient below the middle 
group 90-109, and no child doing ^Very inferior" work 
ranks in intelligence quotient above the middle group. 
The agreement, however, is far from perfect. The 
group doing '^average" school work contains intelligence 
quotients all the way from ^^below 80" to ^^120 or 
above." One child with an intelligence quotient below 



106 STANFORD REVISION OF BINET-SIMON SCALE 

80 is ranked as doing '^superior" school work. The 
correlation by the Pearson formula is .45. 

There are 51 cases out of a total of 504 in which 
the quality of the school work is two steps removed 
from the location required for perfect correlation. 
This is nearly 10 percent of all. An occasional dis- 
agreement of one step would naturally be expected, 
since we know that the quality of school work depends 
partly on factors other than intelligence, such as 
health, industry, conscientiousness, quality of teach- 
ing, etc. But a disagreement of two steps is serious. 

We have examined our data to see if any evidence 
could be found of the presence of constant factors tend- 
ing to explain the disagreement between intelligence 
quotient and quality of school work. In the table are 
26 children whose school work is at least two grades 
better than the intelligence quotient would itself 
warrant. On looking up the facts about these children, 
we find that 19 of them are over-age for their grade. 
Of these, 10 are from two to four years over-age. Of 
course nothing else is needed to explain the disagree- 
ment in these cases. We know it to be true that a 
10-year-old child with a mental age of 8 years (intelli- 
gence quotient 80) is usually just about able to do 
•school work of average quality in the second grade, 
or that a 13-year-old with a mental age of 10 years 
(intelligence quotient 77) can manage to get along 
fairly well in the third or fourth grade. 

Of the other cases of disagreement in this direction, 
4 were kindergarten children. Perhaps these should 
be thrown out altogether, on the ground that the work 
of the kindergarten fails to bring out clearly differences 
of intelligence. Of the remaining cases, one girl of 
8 years was described by the teacher as ^Very timid 



KELATION OF INTELLIGENCE TO SCHOOL SUCCESS 107 

and sensitive/^ and it is possible that this caused an 
unfavorable showing in the tests. Another, also a 
girl, was described as a child of ^Vonderfully sweet 
disposition," that is, the kind of child we are always 
ready to give the benefit of a doubt. In two other 
cases there was an additional explanation, namely, 
an intelHgence quotient which was just over the border 
between two groups. If one of these had tested at 
90 instead of 89, and the other at 110 instead of 109, 
one step of the disagreement would have been elimi- 
nated. Accordingly, we may say that of the 26 cases 
of serious disagreement, 19 are largely accounted for 
by over-ageness, 4 by the fact that the school attended 
was a kindergarten which has no formal work, and that 
in only 2 of the 26 cases was no explanation suggested 
by the data at hand. 

We will now consider the 24 children the quality 
of whose school work ranked two grades below what 
the intelligence quotient would lead us to expect. 
Since over-ageness accounted for nearly two-thirds of 
the disagreements in the other direction, we will nat- 
urally expect to find under-ageness a frequent cause 
of displacement downward. This is true, but to a 
less extent than one might have expected. Of the 24 
children, 10, or nearly 40 percent, are under-age for 
the grade they are in. Seven of these, however, are 
only one year advanced beyond age, a degree of under- 
ageness which would hardly account for more than 
half of the observed disagreement in these cases. 
Four others are kindergarten children and so may be 
left out of account. In one other case the teacher 
had contradicted herself. The child in question had 
an intelhgence quotient of 125 but had been ranked 
only ^ ^average" in school work. The teacher's supple- 



108 STANFORD REVISION OF BINET-SIMON SCALE 

mentar^^ statement, however, showed that the marks 
ranged from B to A in every subject except arith- 
metic, and other statements indicated that the child 
had unusual talent in composition and in the apprecia- 
tion of literature. Two cases were sufficiently ex- 
plained by illness and long absence from school. An- 
other child was described as lazy and incorrigible — 
traits which would affect the school work unfavorably. 
In two other cases about half of the disagreement was 
accounted for by an intelhgence quotient just over 
the dividing line. In the other 4 cases there was 
nothing in our data which suggested a reason for the 
inferiority of the school work below apparent intel- 
lectual ability, though it is possible that a fuller knowl- 
edge of the facts would have cleared up these cases 
also. 

An analysis of the one-step disagreements disclosed 
the same factors, though here there remained a some- 
what larger number for which the data failed to offer 
a clear explanation. This amount of disagreement, 
however, is not particularly significant, since it may 
come about in a great variety of ways having nothing 
to do with the validity of the tests. 

In conclusion we may say that even a two-step 
disagreement between intelligent quotient and the 
quality of a child's school work does not in itself argue 
against the validity of the intelligence test. At least 
90 percent of these disagreements are found to be 
explainable wholly or partly by other facts. It is 
especially to be emphasized that rarely, if ever, is a 
child able to do school work, in the grade where he 
belongs by age, more than one degree superior to that 
which the mental age would lead us to expect. On the 
other hand, it more often occurs that the quality of 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 109 



TABLE 29 
Grade Distribution of 676 Children by Mental Age 



Mental 


Grade Attended 


Age 


I 


II 


III 


IV 


V 


VI 


VII 


VIII 


HS 
I 


HS 
II 


HS 
III 


Total 


8 


25 

25.5% 

4 

4% 


55 
56.6% 


18 

18.4% 


19 

19.4% 


1 

1% 

15 

14.2% 


1 

1% 

6 

5.7% 

17 

20% 


1 

1% 

1 

.9% 

3 

3.5% 

16 

16.6% 


1 

1.2% 

12 

12.5% 

21 

27% 


^^ 






98 


9 


24 

24.5% 

4 

3.8% 


48 
49% 


98 


10 


30 

28.5% 

6 

7% 

1 
1% 

1 

1.5% 


49 
46.6% 


105 


11 


20 

23% 

8 
8.3% 

2 
2.6% 


38 
44.6% 


85 


12 


19 

19.8% 

7 
9% 

4 

6% 


40 
41.1% 


96 


13 


29 

37.1% 

21 
31% 

5 

14% 

2 

16.7% 


19 

24.3% 


78 


14 


16 

23.5% 

10 

28% 

1 


26 

38.2% 


68 


15 
16 


21 

58.5% 

9 

75% 


36 
12 




















676 



110 STANFORD REVISION OF BINET-SIMON SCALE 

the school work drops considerably below the level 
normal to the intelligence quotient in question. The 
chief causes are ill-health, irregularity of attendance, 
or the possession of moral or volitional traits unfavor- 
able to school success. 

Correlation Between Intelligence Quotient and Grade 

Progress 

We have made this comparison for the entire number 
of subjects, but since there is little opportunity for 
children below 8 years to become retarded we have 
included in the following table only those with a mental 
age of 8 years or more. Grade II is regarded normal 
for Mental Age 8, Grade III for Mental Age 9, etc. 
The 8-year mental-age group includes all mental ages 
from 7 years, 7 months, to 8 years, 6 months, and so 
on. 

The table of grade distribution by mental age shows 
that nine-year intelligence is found all the way from 
Grade I to Grade VII, inclusive; ten-year intelligence 
from Grade II to Grade VII, etc. Twelve-year intel- 
ligence, which here ranges from Grade III to Grade 
VIII, would doubtless have been found in the high 
school also, if tests had been made there in any con- 
siderable number. 

Table 30 shows the number and percent who, accord- 
ing to mental age, are retarded or accelerated 1, 2, 3 
or 4 years. The table includes only the Mental Ages 
8 to 16, inclusive. 

Table 30 is given to facilitate comparison with 
the data of others. It should be emphasized, how- 
ever, that the method of expressing the degree and 
amount of retardation and advancement in years 
for children of all ages taken together is misleading. 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 111 



TABLE 30 

Amount of Acceleration and Retardation in the Grades When 
Mental Age is Taken for the Basis 



Grade Below Mental Age 


Normal Grade 

for Mental 

Age 


Grade Above Mental Age 




4 Yrs. 

or 
More 


3 

Yrs. 


2 

Yrs. 


1 
Yr. 


1 
Yr. 


2 

Yrs. 


3 

Yrs. 


4 
Yrs. 


Total 


Number 


4 


13 


69 


184 


275 


106 


22 


3 


1 


676 


Percent 


.5 


1.9 


10.2 


27.2 


40.6 


15.6 


3.2 


.4 


.1 





It overlooks the fact that a given amount of retarda- 
tion or acceleration is not equally significant at the 
different ages. Here, as in the case of mental age, a 
deviation of one year at the age of 8 is as serious as a 
deviation of two years at the age of 16. Obviously, 
when we measure age-grade progress of school chil- 
dren in terms of years of deviation from normal grade 
we are using a unit of measure which has no fixed 
value. Important as this is in the statistical treatment 
of the retardation problem, it has been consistently 
ignored in all of the very numerous studies of age- 
grade progress, from the pioneer work of Ayres on 
down. As a result, all of these studies are mislead- 
ing, particularly in the comparisons made as to the 
^^ amount" of retardation or acceleration at the vari- 
ous ages and in the various grades. 

Reverting to Table 29, it may be pointed out that, 
after the age of 7 or 8 years, misplacement by one 
grade is not especially significant, as that could easily 
happen from any one of a number of causes, such as 
early or late entrance, illness, a little more or a little 
less than average industry, etc. But in 112 cases, or 
nearly 16 percent of all, there is a misplacement of 



112 STANFOKD REVISION OF BINET-SIMON SCALE 

two grades or more. Eighty-five of these, or 123^^ per- 
cent of all, are cases of grade retardation below mental 
age; 26, or nearly 4 percent of all, represent grade 
acceleration beyond mental age. It is interesting to 
note that school retardation of 2 years or more (reck- 
oned on the mental-age basis) is about three times as 
common as acceleration of 2 years or more. On the 
basis of chronological age, the proportion of grade ac- 
celeration to grade retardation is even less than this. 

Our present task, however, is to find an explanation 
of the rather surprising disagreement between grade 
progress and mental age as determined by the scale. 
Taking up first the 26 children whose grade status is 
two or more years ahead of their mental age, we find 
that 19 of these are chronologically over-age for their 
grade. Ten of the 19 are from two to four years over- 
age. In other words, those who are accelerated in 
school on the basis of mental age are usually retarded 
on the basis of chronological age, certainly an inter- 
esting and instructive paradox. The explanation, 
however, is obvious. The school tends to promote 
children by age rather than ability, and although the 
very dull are allowed to become somewhat retarded, 
this retardation is ordinarily less than would be war- 
ranted by their actual mental retardation. For ex- 
ample, there are six children of Mental Age 10 in the 
sixth grade. Two of these are 14 years of age, two are 

15, and one is 16. Of the two children of Mental Age 
11 in the eighth grade, one is 17 years old, three are 

16, and five are 15. Only two are normal age for the 
grade. 

Turning now to the 85 children who are retarded 
two or more grades below the norm for their mental 
age, we find that 23 percent are, on the chronological 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 113 

age basis, actually accelerated, and that over half of 
the remainder are in the grade where they belong by 
chronological age. Only 8 percent of those who are 
retarded two years or more according to mental age 
are retarded as much as two years by chronological 
age. This confirms the suspicion that promotion is 
largely governed by chronological age and helps to 
explain why children of any given mental age are dis- 
tributed over such a wide range of grades. There are, 
of course, other factors which sometimes cause chil- 
dren to be enrolled in grades too low for their mental 
age, e. g., irregularity of attendance, illness, and lack 
of industry. Unfortunately, our blank for supple- 
mentary data did not call specifically for information 
on these points. 

Tables 29 and 30 gave the school progress of the 
children on the basis of mental age. Tables 31 and 32 
give it on the basis of chronological age. Ages below 
8 are disregarded, since at this time retardation and 
acceleration have had little opportunity to occur. 

Comparison of Tables 29 and 31 reveals the striking 
fact that, on the whole, the grade location of school 
children does not fit their mental age much better 
than it fits their chronological age. Except in the 
upper years, children of a given mental age are scat- 
tered over nearly as wide a range of grades as children 
of the corresponding chronological age. Plainly, the 
efforts made at school grading fail to give groups of 
children of homogeneous mental ability. 

That this is largely due to the incorrect grading of 
children of inferior and superior intelligence is easily 
shown by taking those whose intelligence quotient is 
practically normal, say between 96 and 105, and find- 
ing how these distribute themselves in the grades. 



114 STANFOED RE^aSION OF BINET-SIMON SCALE 

TABLE 31 

Age-Grade Distribtttion of Children Aboa^ 7 Years of Age 
(by Chronological Age) 













Grade 








Chron. 
Age 


I 


II 


III 


IV 


V 


VI 


VII 


VIII 


Total 


8 Number 
Percent 


23 
24.5 

5 
4.5 


49 

52.3 


20 

21.2 


2 
1.2 

16 
14.6 


3 

2.7 

17 
20 


2 

2.3 

22 
28.2 


1 

1.2 

5 
6.2 


1 
1.2 

9 
9.5 


94 


9 Number 
Percent 


32 
29.3 

5 
6 

2 
2.6 


53 
48.4 


109 


10 Number 
Percent 


20 

23.5 

7 
9 

5 
6.2 

2 
2 


41 

48.2 


85 


11 Number 
Percent 


18 
23 

8 
10 

7 
7.4 

2 
2.6 

1 
2.1 


28 
36 


78 


12 Number 
Percent 


26 

32 

11 
11.6 

1 
1.3 


36 
44.4 


81 


13 Number 
Percent 


35 
37 

19 

24.3 

2 
4.2 

1 
9 


31 
32.8 


95 


14 Number 
Percent 


19 

24.3 

9 
19.1 

1 
9 


37 
47.5 


78 


15 Number 
Percent 

16 Number 
Percent 


35 
74.5 

9 

8.2 


47 
11 


Total 


















678 



TABLE 32 

Number and Percent of Children Retarded or Accelerated 
1, 2, 3, OR 4 Years for the Ages 8-14 Combined 







Retarded 


In Grade 
for Age 


Accelerated 




















Total 




4 


3 


2 


1 




1 


2 


3 




Number 


4 


15 


55 


173 


275 


89 


9 


1 


620 


Percent 


.6 


2.4 


8.8 


27.9 


44.3 


14.3 


1.4 


.1 


100 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 115 

This method gives the correlation relatively freed 
from the constant tendency of teachers to over-pro- 
mote the dull and under-promote the superior chil- 
dren. Table 33 gives this distribution. 



TABLE 33 

Grade Distribution by Chronological Age op Children with 
Intelligence Quotient between 96 and 105 



Chron. 


Grade 


Age 


I 


II 


III 


IV 


V 


VI 


VII 


VIII 


Total 


8 


9 


25 


4 


3 


3 


2 




1 


38 


9 


10 


25 


38 


10 


10 

2 


19 


32 


11 


5 
1 


17 


26 


12 


9 
1 
1 


10 


20 


13 


15 
6 


14 


31 


14 


8 
4 


15 


30 


15 
16 


7 
1 


11 
1 


Total 


31 


42 


41 


28 


31 


33 


26 


24 


227 



116 STANFORD REVISION OF BINET-SIMON SCALE 

Of the 227 children appearing in the above table, 
only 4 who are below the age of 14 are more than one 
grade removed from the place where they belong by 
chronological age. All the two-grade displacements 
are in the direction of retardation. That is, the child 
with an intelligence quotient between 96-105 is never 
found (in our data) two grades advanced in school; 
and the chances are about 50 to 1 that if he is under 
14 years of age and tests between 96-105 he will not 
be as much as two years retarded. (Of 198 children 
with ages 8-13, 4 are retarded two years.) At ages 14 
and 15 selection has taken place and the proportion of 
retardation is naturally much larger. 

Another interesting comparison may be made by 
taking the extreme intelUgence quotients and finding 
the location in the grades for the exceptionally dull 
and exceptionally bright children of each chronological 
age. We have done this for the intelligence quotients 
above 120 and below 80. The results are shown in 
Tables 34 and 35. 

Of the 68 children appearing in Table 34, full supple- 
mentary information is available regarding 34. Of 
these, not one is doing less than ^'average" work in 
the grade attended, while 23 are graded as doing 
either ^' superior'^ or '^very superior" school work. Of 
the 8 who are advanced two grades beyond chrono- 
logical age, we have supplementary information re- 
garding 5. Of these 5, every one is graded as doing 
either '^superior" or ^^very superior" work, and every 
one is ranked by the teacher as either "superior" or 
'^very superior" in intelligence. 

It will be noted that of the 54 children 7 years old 
or above, 15 are in the grade where they belong by 
chronological age, while 3 are even retarded one year 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 117 



TABLE 34 

Age-Grade Distribution of Children with Intelligence Quotient 120 

OR Above 



Chron. 


Grade 


Age 


Kgn. 


I 


II 


III 


IV 


V 


VI 


VII 


VIII 


Total 


6 


2 


11 


1 














14 


7 




6 


3 


2 












11 


8 






1 


7 


2 

5 


1 
1 








11 


9 






6 


10 








1 


3 


3 


1 

6 


3 


2 


8 


11 


1 


1 


8 


12 




3 


6 


13 


1 


1 


4 


14 








15 






16 






















Total 


2 


17 


5 


10 


11 


6 


11 


4 


2 


68 



118 STANFOnD TIEVISION OF BTNKT-RTMON SCALE 

by chronological i\y:,v. That is, IS, or one-third of all 
those 7 years old or older having an intelligence quotient 
of 120 or above fail to reap any advantage {as far as pro- 
niolurn is concerned) from tJieir very superior intelli- 
gence. They nrc all doiiij;- 'Scry superior" to 'Sivcr- 
afz;i^" school Avork and would (loubllcss (Hniiinue the 
sninc record if accorded t he vxivn i)roniot ions warranted 
by their intelligence ({uotient. The n^luctance of 
teachers to give sucli promotions is probably due both 
to inertia and to an \niwiHingness to part with excep- 
tionally satisfactory ])upils. 

Of the 12 children appearing in the above table, all 
of whom have between two-thirds and four-fifths in- 
t(*Hig(Mict» (intelligence (|uotient 05 to SO), only two are 
in the grade where they bi^long by chronological age. 
Jioth of these W(M'e doing "very infiM'ior" s(^hool work 
and neither was promoted the following year. Six of 
the 42 are only one year retarded. Su|)pltMnentaiy 
data are available for only four of the six. Two of 
these four are doing 'Wery inferior" work, two '* in- 
ferior" work. Of tlie 18 an ho are retarded two years, 
supplemtMitary data are available for 1 1, four of whom 
are said to be doing "average" work, four "inferior" 
work, and three 'Wery inferior" work. Of the 10 re- 
tarded three years or more, we have supplementary 
data for 10, three of whom are doing '^average" work, 
four "inferior," and three "very inferior." It is inter- 
esting to note that two of the tlu'ce w^ho are doing 
"average" work are fonr years retarded: one is 13 
years old and in the tliird grade, the other is 14 years 
old and in the fourth grade. This is really what we 
should (^xpect of high-grade feeble-minded children of 
i;> and 14 years. 



RELATION OF INTELLKHONCE TO BCIIOOL SUCCEBB 119 



'I'AItLIO ;{5 
Aaro-GuADK Dihtuibution of CiiiummN with Intki.kkjknok (^i/o- 

TIKNTS liWLOVV 80* 



Ofiron. 








Orado 










Ak<5 


1 


II 


III 


IV 


V 


VI 


VII 


VIII 


ToUl 


8 


2 
3 
















2 


9 


2 
4 
1 




5 


10 


2 
4 
1 




4 


11 


2 
5 
1 




3 


12 


2 




6 


13 


1 

2 
1 


2 


11 


14 


1 
1 
1 




3 


15 
16 

17 


1 
2 
1 


3 
3 
2 


Total 


5 


7 


7 


8 


2 


4 


5 


4 


42 



* (35 of the 42 have intolllgenccj quotients between 70-79.) 



120 STANFORD REVISION OF BINET-SIMON SCALE 

The foregoing is suggestive because indicative of 
what three-quarter intelUgence can do. A child of 
this degree of deficiency is usually two to four years 
below grade for his age, and his work is usually ''infer- 
iors^ or ''very inferior. '^ Rarely is he found in the 
grade where he belongs by chronological age and he 
never does better than "inferior" work there. 

We learn less from Table 34 of what pupils of intelli- 
gence quotient 125 can do than we do from Table 35 
of what pupils of intelligence quotient 75 can do. The 
reason is that the school does not often give the superior 
child a chance to work up to his proper level of per- 
formance. Compared to their possibilities, children of 
exceptionally superior intelligence are usually retarded, 
just as we found exceptionally inferior children almost 
always above the grade where they belong by mental 
age. Most of the apparently much-retarded children 
are really accelerates; many of the exceptionally 
accelerated children are really retardates. 



TABLE 36 

Correlation Between Intelligence Quotients and Intelligence 
Estimated by the Teachers 



Teachers' 


I Q 


Estimates 
















Below 80 


80-89 


90-109 


110-119 


120 and up 


Total 


Very Superior 
Superior 
Average 
Inferior 
Very Inferior 



2 

10 
11 

8 


2 
3 

37 

22 

4 


7 

60 

184 

34 

6 


4 

29 

39 






3 
17 
7 




16 
111 

277 
67 
18 


Total 


31 


68 


291 


72 


27 


389 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 121 

By the Pearson formula the correlation contained in 
Table 36 is 0.48. This is about what others have 
found, and is both large enough and small enough to 
be significant. That it is moderately high in so far 
corroborates the tests : that it is not higher means that 
either the teachers or the tests have made a good many 
mistakes. 

We note first that 24 children in the above table are 
placed two steps higher in the teachers' estimates than 
the intelligence quotient would suggest, while only 13 
are displaced two steps downward. This discrepancy 
would indicate that there is probably some factor caus- 
ing teachers to overestimate the intelligence of those 
whose test performance is low. On looking into the 
matter we find that of the 24 children misplaced up- 
ward by the teachers' estimates, 14 are from two to 
four years over-age for their grade. These cases are, 
therefore, sufficiently explained. It is the teachers 
who were at fault, not the scale. In judging the intel- 
ligence of these children they forgot to make allowance 
for the over-ageness. Finding them about on a par 
in intellectual maturity with other children of their 
classes, they judged them equally intelligent. 

Of the remaining 10 children in this group, three 
were in the kindergarten, where the teacher has little 
opportunity to form an opinion as to a child's intelli- 
gence. In another case, that of a boy with an intelli- 
gence quotient below 80 who was ranked ^^ average," 
the teacher had contradicted her own estimate by 
adding an explanatory note which made it clear that 
the boy was probably a borderline case or even feeble- 
minded, though possessed of some ability to profit by 
drill work suited to children a year or two below his 
age. In four other cases the intelligence quotient was 



122 STANFORD REVISION OF BINET-SIMON SCALE 

just over the dividing line, making the disagreement 
between it and the teacher's estimate appear ahnost 
twice as great as it really was. In only two of the 24 
cases was there no information at hand that would 
explain all, or nearly all of the disagreement. 

Of the 13 who were displaced two steps downward 
in the teachers' estimates, we find that five were from 
one to two years under-age for their grade. Their 
intelligence had accordingly been judged by a standard 
which was unfair to them; that is, by a standard based 
upon the average intelligence of older children. Two 
were kindergarten children. In another case the 
teacher, after ranking the child in the ^'very inferior" 
group, added a note saying that the child was very 
deaf and that this might account for the apparent 
stupidity. The test gave this child an intelligence 
quotient of 95, which was probably not far from cor- 
rect. Half the disagreement could be accounted for 
in two other cases by the presence of the intelligence 
quotient near the dividing line. This leaves 3 cases of 
two-step downward displacement still unexplained, 
though we are inclined to suspect that if more facts 
were available, these, too, could have been cleared up. 

Similar reasons appear to account for approximately 
half of the one-step disagreements. When all the ex- 
plained disagreements were eliminated from Table 
9, the correlation rose from .48 to .71. 

Another way to get at the degree of agreement be- 
tween intelhgence quotients and the teachers' esti- 
mates (as the latter would be if freed from the con- 
stant error due to neglect of age differences) is to com- 
pute the correlation separately for those children who 
are in the grade where they belong by chronological age. 
When this is done the coefficient of correlation, as may 
be found from Table 37, rises from .48 to .57. 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 123 

TABLE 37 











I Q 






Teacher's 














Estimates 
















Below 80 


80-89 


90-109 


110-119 


120 or above 


Total 


Very superior 








1 


3 


2 


6 


Superior 








27 


20 


3 


50 


Average 





6 


80 


16 


1 


103 


Inferior 





4 


12 








16 


Very inferior 


1 


3 


2 








6 


Total 


1 


13 


122 


39 


6 


181 



Still another method of showing how strongly 
teachers tend to base their estimate of a child's intel- 
ligence upon the quality of his school work, to the 
neglect of age differences, is to take their classification 
of a group of children according to intelligence, and 
their classification of the same children according to 
school work, and ascertain the degree of correlation 
between the two groupings. We have done this, with 
the result shown in Table 38. 

TABLE 38 

Correlation Between the Teachers' Groupings According to 
Intelligence and According to Quality of School Work 



Teachers' 
Classification 


Teachers' Classification According to Intelligence 


according to 
School Work 


Very 
Inferior 


Inferior 


Average 


Superior 


Very 
Superior 


Total 


Very Superior 
Superior 
Average 
Inferior 
Very Inferior 






4 
13 





12 
45 
11 



16 

212 
35 

2 


3 

83 

22 

1 




12 
6 





15 

105 

246 

85 

26 


Total 


17 


68 


265 


109 


18 


477 



124 STANFORD REVISION OF BINET-SIMON SCALE 

The correlation is .82 and would probably have been 
still higher if the supplementary form filled out by the 
teachers had not contained the specific instruction to 
estimate the intelligence of a child "in comparison 
with other children of the same ageJ^ In spite of this 
injunction, they have obviously ignored age differences 
and estimated intelUgence chiefly on the quality of 
the child's school work in the grade where he happened 
to be. They have failed to realize that quality of 
school work is no index of intelligence unless age is 
taken into account. The question should be, of course, 
not: '4s this child doing his school work well?" but 
rather: "m what school grade should a child of this 
age be doing satisfactory work?" A high-grade im- 
becile may do average work in the first grade and a 
high-grade moron average work in the third or fourth 
grade, provided only they are sufficiently over-age for 
the grade in question. 

Our experience in testing children for segregation in 
special classes has time and again brought this peculiar 
fallacy of teachers to our attention. We have often 
found one or more feeble-minded children in a class 
after the teacher had confidently asserted that there 
was not a single exceptionally dull child present. In 
every case where there has been opportunity to follow 
the later school progress of such a child the substan- 
tial accuracy of the mental test has been confirmed. 

The following are typical examples of the neglect of teachers to take 
the age factor into account when estimating the intelligence of the 
child over-age for his grade : 

A. R. Boy, age 17, mental age 11, sixth grade, school work "nearly 
average," teacher's estimate of intelligence ''average." Test plainly 
shows this child to be a high-grade moron, or borderliner at best. Had 
attended school regularly 11 years and had made 6 grades. Teacher 
had compared child with his 12-year-old classmates. 

H. A. Boy, age 13, mental age 9-6, low fourth grade, school work 
''inferior," teacher's estimate of intelligence "average." The teacher 



KELATION OF INTELLIGENCE TO SCHOOL SUCCESS 125 

blamed the inferior quality of school work to "bad home environ- 
ment." As a matter of fact, the boy's father is feeble-minded and the 
normahty of the mother is questionable. An older brother is in a 
reform school. We are perfectly safe in predicting that this boy will 
not complete the eighth grade, even if he attends school till he is 21 
years of age. 

F. I. Boy, age 12-11, mental age 9-4, third grade, school work 
"average," teacher's estimate of intelligence "average," social environ- 
ment "average," health good and attendance regular. Intelhgence 
and school success are what we should expect of an average 9-year old. 

D. A. Boy, age 12, mental age 9-2, third grade, school work "in- 
ferior," teacher's estimate of intelligence "average." Teacher im- 
putes inferior school work to "absence from school and lack of inter- 
est in books"! We have yet to find a child of 75 intelligence quotient 
who was particularly interested in books or enthusiastic about school. 

C. U. Girl, age 10, mental age 7-8, second grade, school work 
"average," teacher's estimate of intelligence "average." Teacher 
blames adenoids and bad teeth for retardation. No doubt of child's 
mental deficiency. 

P. I. Girl, age 8-10, mental age 6-7, has been in first grade two 
years and a half, school work "average," teacher's estimate of intelh- 
gence "average." The mother and one brother of this girl are feeble- 
minded. 

H. O. Girl, age 7-10, mental age 5-2, first grade for 2 years, school 
work "inferior," teacher's estimate of intelligence "average." The 
teacher, nevertheless, adds: "This child is not normal, but her ability 
to respond to drill shows that she has intelhgence." It is true that 
even feeble-minded children of 5-year intelhgence are able to profit a 
httle from drill. Their weakness comes to light in their inabihty to 
perform higher types of mental activity. 

The following are examples of the under-estimation 
of intelligence and school ability of children who are 
under-age for their grade: 

M. L. Girl, age 11-2, mental age "average adult" (16), sixth 
grade, school work "superior," teacher's estimate of intelhgence 
"average." Teacher credits superior school work to "unusual home 
advantages." Father is a college professor. The teacher considers 
the child accelerated in school. In reahty, she ought to be in the 
second year of the high school, instead of in the sixth grade. 

H. A. Boy, age 11, mental age 14, sixth grade, school work "aver- 
age," teacher's estimate of intelhgence "average." According to the 
supplementary information the boy is "wonderfully attentive," 
"studious," and possessed of "aU-round ability." The estimate of 
"average intelhgence" is probably due to the fact that he was com- 
pared with classmates who averaged about a year older. 

K. R. Girl, age 6-1, mental age 8-5, second grade, school work 
"average," teacher's estimate of inteUigence "superior," social environ- 
ment "average." Is it not evident that a child from ordinary social 



126 STANFORD REVISION OF BINET-SIMON SCALE 

environment who does work of average quality in the second grade 
when barely 6 years of age, and who has an intelligence quotient of 
about 140, should be judged "very superior" rather than merely 
"superior" in intelligence? 

S. A. Boy, age 8-10, mental age 10-9, fourth grade, school work 
"average," teacher's estimate of intelligence "average." Teacher 
attributed school acceleration to "studiousness" and "dehght in 
school work." Our own guess would be that these traits are, rather, 
indications of unusually superior intelligence- 
Ill a special study of a group of superior children, 
tested separately from the present investigation, we 
have found even more striking examples of the difficulty 
teachers have in recognizing superior ability. One 
case was that of a boy aged 10-6 with an intelligence 
quotient of 148. He was in the sixth grade, doing 
'' superior '^ work there, and yet was judged by the 
teacher to have '^no unusual ability." It was learned 
from the parents that the boy is distantly related to 
Meyerbeer, the composer, and that at an age when 
most children are reading fairy stories, he has a passion 
for difficult medical literature and text books in phys- 
ical science. 

The question has suggested itself, whether teachers^ 
estimates of intelligence vary in reliability with chil- 
dren of different ages. We have divided our children 
into three groups, according to age, and have com- 
puted for these groups separately the correlation 
between the intelligence quotient and the teachers' 
estimates. Ages 5, 6, 7 and 8 were placed in one 
group; Ages 9, 10 and 11 in another; and Ages 12, 13, 
14, and 15 in a third. The coefficients were, in order, 
.48, .60 and .46. It appears, therefore, that teachers 
probably make fewer errors with pupils of the middle 
group, though the difference is not great. 

Such facts as we have set forth in this chapter sug- 
gest that, while the judgment of a teacher regarding a 



RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 127 

child's school success and intelligence may, if properly 
safeguarded, afford valuable data to supplement the 
results of the intelligence test, the assistance is more 
likely to be in the other direction; more often it is the 
test which can keep us from being misled by the 
erroneous judgment of the teacher. 

SUMMARY 

1. The correlation between intelligence quotient and 
the quality of the school work as judged by the teachers 
is .45. An examination of the marked cases of dis- 
agreement between intelligence quotient and school 
work shows that these are due largely to the teachers' 
neglect of age differences in estimating quality of 
school work. 

2. The correlation between intelligence quotient and 
the teachers' rankings according to intelligence is .48. 
Detailed study of the cases of disagreement justifies 
the conclusion that they are due mainly to certain 
constant errors to which teachers are subject in esti- 
mating a child's intelligence. Here, as in judging 
quality of school work, the most common error is that 
of overlooking age differences. Teachers judge in- 
telligence mostly by the quality of school work in the 
grade where the child happens to be located. This 
results in over-estimating the intelligence of older, 
retarded children, and under-estimating the intelligence 
of the younger, advanced children. 

3. The wider disagreements between intelligence 
quotient and grade status are confined chiefly to those 
children who are superior to, or below the average in 
ability. The explanation for this has been found in 
the fact that the tendency of the school is to promote 
children by age rather than by ability. Those who 



128 STANFORD REVISION OF BINET-SIMON SCALE 

have an intelligence quotient between 96 and 105 are 
hardly ever more than one grade removed from the 
location which is normal to their mental age. 

4. The child with an intelligence quotient of 120 or 
above is rarely found below the grade for his chrono- 
logical age, and occasionally he is one or two grades 
above. Wherever located, his work is nearly always 
superior, and the evidence suggests strongly that this 
superiority of school work would continue even if 
extra promotions were granted. Superior children are 
seldom allowed to reap the advantage, in school prog- 
ress, to which their superiority fairly entitles them. 

5. The child of 70-79 intelligence quotient never 
does satisfactory work in the grade where he belongs 
by chronological age. After the age of 8 or 9 years 
such a child is usually found doing ''very inferior" to 
''average" work in a grade two to four years below his 
age. 

6. Although the disagreements between intelhgence 
quotient on the one hand and grade progress, quality 
of school work, and teachers' estimates of intelligence 
on the other hand would at first seem to justify serious 
misgivings as to the value of the intelligence scale, 
these same disagreements, on closer examination, are 
found to offer the strongest evidence in support of the 
test method. 



CHAPTER VII 

THE VALIDITY OF THE INDIVIDUAL TESTS 

Criteria of a Tesfs Validity 

The first task in the construction of an intelligence 
scale is to select tests which are really tests of intelli- 
gence, tests which are not too much influenced by age, 
home environment or school instruction apart from 
native endowment. There are three criteria which a 
test must satisfy before it can be accepted as a valid 
measure of intelligence. In the first place, since we 
know that intelligence is to a certain extent a function 
of age, a test to be valid must show an increase from 
year to year in the percentage of unselected children 
that pass it. This is the criterion on which Binet 
chiefly rehed. Nearly all the tests which he finally 
included in his scale satisfy this criterion fairly well, 
though some show a more rapid increase than others. 

This, however, is not sufficient. Many other traits 
besides intelligence are also functions of age. Height, 
weight, chest girth, length of forearm, in fact, any 
physical trait influenced by growth would show a 
steady increase from age to age in the percentage 
that pass a given standard. Yet it is easy to show that 
tests of this kind have no place in an intelligence scale. 
If 100 unselected 10-year-olds were measured for 
length of forearm it would of course be found that the 
average for all considerably exceeds that for 9-year 
olds; but it would also doubtless be found that this 
is little if any more true of 10-year-olds who have 
superior intelligence than of 10-year-olds who have 
inferior inteligence. That is, although intelligence and 

129 



130 STANFORD REVISION OF BINET-SIMON SCALE 

length of forearm are both functions of age, they have 
no direct relationship to each other. Such a test 
would not be found coherent with any already existent 
intelligence scale. Similarly, if a given test in the 
Binet series does not agree with the scale as a whole, 
if 10-year children who by the scale have 11-year intel- 
ligence do not pass it any more frequently than those 
10-year children who have 9-year intelligence, then 
either this test is worthless or the scale as a whole 
lacks validity. The entire scale must be coherent. 

But coherency and age-increase in the percentage 
that pass do not themselves guarantee the validity of 
a series of tests for the measurement of intelligence. 
A set of tests made up of a great variety of physical 
measurements might very well satisfy both of these 
criteria. If we have no already existing intelligence 
scale with which to compare an individual test, then 
we must compare the test with intelligence as other- 
wise estimated, for example, with teachers' rankings. 
If children who are ranked as intelUgent succeed with 
it no better than those who are ranked as dull, then 
the test is of doubtful validity. 

For our present purposes the third criterion may be 
left out of account in judging the validity of individual 
tests of the Binet scale. It has been amply demon- 
strated that the scale as a whole gives a fairly reliable 
index of intelligence. Its results always show a 
reasonably high correlation with intelligence as judged 
by teachers or other observers. We have already 
shown that its correlation with school success is fairly 
high, particularly when allowance is made for certain 
tendencies to error in the estimation of school success. 
Its use with feeble-minded children in institutions has 
been especially convincing. Long-continued observa- 



VALIDITY OF THE INDIVIDUAL TESTS 131 

tion of such children rarely necessitates any serious 
correction of its verdict. 

As for the first essential — the requirement of an 
increase in the percentage of passes from year to year 
— ^it is evident from all the available statistics that all 
the tests which we have included in the revision meet 
this criterion in a fairly satisfactory way. Some tests 
show more rapid increases than others, but not one is 
passed by equal percentages in three successive years. 

Accordingly, the criterion of most importance for 
our purpose is the second one — that of coherency. 
Since we know that the scale as a whole is fairly reli- 
able, we can measure each individual test against the 
entire scale. A test which gives results out of harmony 
with the results of the scale as a whole can not be con- 
sidered a satisfactory test of intelligence, whatever 
increase it may show in the percentage that pass it 
from year to year. This increase might be due to 
other factors than intelligence, such as school instruc- 
tion or the incidental experiences which come with 
increasing age. 

One way of applying this criterion would be to classify 
all our subjects by mental age as determined by the 
scale and then note the number that pass a given test 
at successive mental ages. This method gives valu- 
able information, and we have had to rely on it to a 
large extent in evaluating and placing the tests of the 
upper-year groups. It has, however, one objectionable 
feature; the results are more or less influenced by age, 
apart from intelligence. Children of 8-year mental 
age, for example, range in chronological age all the way 
from 53^ or 6 years to 11 or 12 years, and it is conceiv- 
able that these large age differences might have a 
considerable influence on the number that pass a given 



132 STANFORD EEVISION OF BINET-SIMON SCALE 

test. The only way to separate the influence of intelli- 
gence from that of age is to take a large number of 
unselected children of one chronological age and find 
the percentage of passes separately for the bright and 
dull children of that group. 

Correlation of the Individual Tests with Intelligence 

Quotient 

Following the foregoing plan, we have divided the 
children of each chronological age into thi*ee groups 
according to magnitude of intelligence quotient. We 
have placed in the middle or normal group those chil- 
dren of a given age having an intelligence quotient 
between 96 and 105, in the inferior group those with 
an intelligence quotient below 96, and in the superior 
group those with an intelligence quotient of 106 or 
above. At most of the ages this gives three groups of 
about the same size. Had we tested a larger number 
of children of each age, it would probably have been 
better to place more children in the middle group, say 
all between 91 and 110 intelligence quotient. This 
would have heightened the contrast between the inferior 
and superior groups. However, such a plan would 
have placed about 60 percent of our cases of a given 
age in the middle group and left only about 20 percent, 
only 12 to 20 children, for each of the other groups. 
Accordingl}'-, in order to obtain three groups of nearly 
equal size we have included in the middle group those 
with an intelligence quotient between 96 and 105. 

Table 39 shows the results of this comparison. The 
figures are in all cases the percentages of passes for 
children of the chronological age in which the test is 
located. The three columns give these percentages 
for children with intelligence quotient 95 or below, 
96-105, and 106 or above, respectively. 



VALIDITY OF THE INDIVIDUAL TESTS 



133 



TABLE 39 



a CO 



.g 



fl o 






fin ^ 



tiD 


6D 




C3 


is 


•*^ t-i 


+3 o 


!=^ 7 


sa o 


© te 


® . 


^ q 


"to 


© © 


<a 


PU ^ 


Ct( i-i 



V 

1. Weights 

2. Colors 

3. Aesth. Comp 

4. Def . by use. . 

5. Patience. . . . 

6. Commissions 
Al. Age 



VI 

1. Right and left. . . . 

2. Mutilated pict 

3. Thirteen pennies. . 

4. Comprehension (2) 

5. Four coins 

6. 16-18 syllables . . . 
Al. A.M. and P.M.... 



VII 

1. Fingers 

2. Descript. of picture. . 

3. Five Digits 

4. Bow knot 

5. Differences 

6. Diamond 

Al. Days of week 

Al. Three Digits Reversed 

VIII 

1. BaU and field 

2. 20-1 

3. Comprehension (3) . . . 

4. Similarities 

5. Superior def 

6. Vocabulary (20) 

Al. Six Coins 

Al. Dictation 



53 
58 
58 
52 
47 
43 
53 



43 
32 
40 
50 
54 
57 
64 



53 
48 
62 
43 
48 
38 
ZZ 
39 



48 
35 
52 
44 
44 
26 
53 
65 



75 
75 
69 
69 
75 
75 
69 



70 
66 
77 
68 
79 
65 
82 



68 

52 
74 
71 
74 
58 
62 
55 



60 
55 
80 
57 
60 
57 
64 
90 



84 
89 
84 
79 
95 
90 
95 



89 
86 
96 
85 
83 
78 
86 



85 
80 
80 
78 
95 
82 
85 
75 



69 

83 
80 
83 
80 
74 
71 
100 



IX 

1. Date 

2. Weights 

3. Change 

4. Four Digits Reversed 

5. Three words 

6. Rhymes 

Al. Months 

Al. Stamps 



X 

1. Vocabulary (30) 

2. Absurdities 

3. Designs 

4. Reading and rept. . . . 

5. Comprehension (4) . . . 

6. Sixty Words 

Al. Six Digits 

Al. 20-22 SyUables 

Al. Healy's form board. . . 

XII 

1. Vocabularj^ (40) 

2. Abstract words 

3. Ball and field 

4. Disarranged sentence 

5. Fables (score 4) 

6. Five Digits Reversed . 

7. Picture interpreted. . . 

8. Similarities 

XIV 

1. Vocabulary (50) 

2. Induction 

3. President and K 

4. Prob. of fact 

5. Arith. reas 

6. Clock* 

Al. Seven Digits 



48 


68 


37 


58 


39 


60 


45 


62 


49 


67 


39 


67 


39 


55 


40 


76 


20 


60 


35 


60 


45 


57 


45 


63 


25 


64 


30 


70 


55 


67 


45 


57 


55 


67 


36 


70 


40 


60 


36 


65 


45 


60 


39 


70 


48 


75 


21 


60 


47 


65 


42 


76 


41 


59 


22 


62 


44 


55 


25 


55 


59 


83 


50 


62 



Figures for clock problem are on basis of 1 success out of 2 trials. 



134 STANFORD REVISION OF BINET-SIMON SCALE 

Table 39 contains not a few surprises. Some of the 
tests which have been most criticized for their sup- 
posed dependence on extraneous factors here show a 
high correlation with intelligence. Among these are 
'^days of week," '^ stamps/' ''13 pennies/' ''president 
and king/' "rhymes/' "age/' "right and left" and 
"picture interpretation." Others having a high reli- 
ability are "vocabulary/' "arithmetical reasoning/' 
"giving differences/' "diamond/' "date/' "reversed 
digits/' "fables/' "disarranged sentences/' "60 words/' 
"mutilated pictures" and "absurdities." 

Among the poorest are "repeating digits" (direct 
order), "naming coins," "morning and afternoon," 
"definition by use," "designs" and "aesthetic com- 
parison." Three of the tests which had been included 
in our original trial series correlated so little with in- 
telligence that we have thrown them out. They are 
Binet's suggestion test (in his 1911 revision), Healy 
and Fernald's Construction Puzzle B, and our test of 
drawing an apple with a pencil through it. The 
figures for these tests are as follows: 

TABLE 40 





Percent 

passing 

below I Q 

96 


Percent 
passing 

IQ 
96-105 


Percent 

passing 

above I Q 

105 


Binet's suggestion test (Yr. X) 
Healy and Fernald Construction 

Puzzle B (Yr. XII) 
Drawing apple and pencil (Yr. VIII) 


80 

75 
62 


62 

75 

63 


89 

65 
57 



Tests that correlate moderately with intelligence 
include "arranging weights," "three commissions," 
"colors," "fingers," "picture description," "months," 
"change," "similarities," "superior definitions," "read- 



VALIDITY OF THE INDIVIDUAL TESTS 135 

ing for memories," ^'abstract words," '^induction 
test," ^^ problems of fact," ^^ clock" and ^^ bow-knot." 

A test that makes a good showing by this method 
of comparison, whatever it appears to be from mere 
inspection, is a real measm-e of intelligence. Hence- 
forth, it stands or falls with the scale as a whole. That 
so few of the tests should fail to show a reasonably 
high correlation with intelligence is striking evidence 
of the ingenuity and psychological insight of Binet. 

It is especially interesting to compare the facts set 
forth in Table 39 with Meumann's classification of the 
tests as ^Hests of maturity," 'Hests of milieu ^'^ and 
'Hests of endowment." Of the good or superior tests, 
Meumann has classified the following as tests of 
milieu: ^^ counting pennies," ^'colors," '^vocabulary," 
''days of week," "months," "date," "right and left," 
"20-0," "ball and field," and "60 words." Other 
excellent tests of intelligence he classifies as tests of 
maturity. In the light of our results it is hardly neces- 
sary to enter into the a priori criticisms which Decroly 
and Degand, Ayres, and others have made of certain 
of the tests. The classification and criticism of tests by 
mere inspection may form an interesting pastime, 
but it can hardly be taken seriously as a contribution 
to science. 

It is not imphed that a test which makes a good 
showing in Table 39 is entirely free from other influ- 
ences than intelhgence. On the contrary, age and 
environment may affect almost every test to a greater 
or lesser degree. To determine the exact extent to 
which this may be true for even a single test, would 
require an extensive investigation. 



136 STANFORD EEVISION OF BINET-SIMON SCALE 

The Influence of School Instruction 

We have the following data to offer regarding the 
influence of school instruction upon certain of the 
tests in the highest groups. A comparison was made 
of the percentages of passes made on individual tests 
by '^educated" and by '^ little-educated" adults who 
tested at the '^average adult" level, that is, between 
15 and 17 mental age. Of the adults tested by Knol- 
lin, Johnson, Zeidler and Terman there were 28 of the 
^'average adult" level who had progressed through 
the high school or beyond and 33 who had not gone 
beyond the eighth grade. Of those who reached the 
^^ superior adult" level (17-19 mental age) there were 
17 of high-school education and 15 of conunon-school 
education or less. Table 41 shows the percentages of 
passes of these two groups on each test in the four 
highest groups of tests. 

The striking thing in this table is the evident lack of 
any significant influence of school training on the 
ability to pass most of the tests. The only ones in 
which the high-school group shows a marked super- 
iority are ^^ sense of selection," 'ingenuity," ^^ abstract 
pairs" (XVI) and '^problems of fact." The common- 
school group has the advantage in ^^ball and field," 
^'5 digits reversed," ''6 digits reversed," "7 digits" 
(direct order) and '^26-28 syllables." ^'Vocabulary," 
'^fables," ''paper cutting" Binet, "clock," "arith- 
metical reasoning," and "disarranged sentences" show 
no significant difference between the two groups. 

We have often been warned by skeptical friends 
that size of vocabulary is determined by schooling and 
not by intelligence, that success with the fables de- 
pends wholly upon moral instruction, that "arith- 



VALIDITY OF THE INDIVIDUAL TESTS 



137 



TABLE 41 

Percentages op Average and of Superior Adults Who Pass 
Several Tests of Age XII and Above 



THE 



Test 



" Average Adults " 
(15-17 mental age) 



H. S. 
Group 



Com. Sch. 
Group 



"Superior Advilts" 
(17-19 mental age) 



H. S. 
Group 



Com. Sch» 
Group 



XII 

1. Vocabulary (40) 

2. Abstract words 

3. Ball and Field 

4. Disar. Sentences 

5. Fables (score 4) 

6. Five digits reversed . . 

7. Pict. interpret 

8. Similarities 

XIV 

1. Vocabulary (50) 

2. Induction 

3. Pres. and king 

4. Prob. of fact 

5. Arith. reas 

6. Clock* 

Al. Seven digits 

XVI 

1. Vocabulary (65) 

2. Fables (8).. _ 

3. Abstract pairs 

4. Box problem 

5. Six digits reversed . . . 

6. Code 

XVIII 

1. Vocabulary (75) 

2. Paper cutting 

3. Eight digits 

4. Sense of selection. . . . 

5. Seven digits reversed 

6. Ingenuity 



100 
94 
70 
94 
90 
74 
97 
97 



100 
97 
89 
97 
89 
91 
60 



90 
79 
91 
51 
34 
38 



35 

30 
30 
63 

no data 
42 



100 
97 
85 
91 
94 
92 
84 
85 



97 
85 
83 
85 
79 
85 
90 



85 
74 
73 
76 
61 
26 



30 

28 
34 
28 
no data 
20 



100 
100 

84 
100 
100 

93 
100 
100 



100 
100 
100 
100 

94 
100 

93 



100 
86 

100 
86 
73 
75 



100 

77 

73 

81 

no data 

85 



100 
100 

90 
100 

95 

95 
100 

90 



100 
95 

87 

100 

96 

95 

87 



100 

82 

100 

95 

77 
67 



83 
89 
67 
57 
no data 
70 



Figures for clock test are on the basis of 1 success in 2 trials. 



138 STANFORD REVISION OF BINET-SIMON SCALE 

metical reasoning" and the '^paper-cutting" test will 
be greatly influenced by recency of instruction in 
arithmetic and geometry, respectively, and that the 
ability to repeat sentences and digits depends almost 
purely upon that rote memory which is so diligently 
cultivated in the schools. From the data presented 
above, however, it is evident that criticisms based on 
off-hand opinion have little value. 

The Influence of Age and Experience 

The influence of maturity, apart from native endow- 
ment, is difficult to isolate. We can, of course, compare 
older and younger individuals of the same mental age 
with respect to the percentages that pass individual 
tests, but this gives us the combined influence of ma- 
turity and experience. The 16-year-old of 10-year 
intelligence is not only more mature than the 10-year- 
old of 10-year intelligence; he has had also the advan- 
tage of 6 years additional experience and opportunity 
to learn. The best we can do, however, is to treat 
these two influences as one, which we may call the 
''age factor," meaning thereby the combined influence 
of age, as such, and of the experience which goes with 
age. 

The influence of the "age factor" may be seen by 
comparing Williams' delinquents and Knollin's un- 
employed of a given mental age with unselected school 
children of that chronological age. Such comparisons 
were made for the Mental Ages 9 to "average adult." 
It will be remembered that most of the delinquents 
were between 12 and 21 years of age and that most of 
them were mentally retarded (nearly a third were 
classed as feeble-minded). The unemployed were 
somewhat less inferior and ranged from 20 to 65 years 



VALIDITY OF THE INDIVIDUAL TESTS 139 

of age, with a median of 34 years. Accordingly, if the 
dehnquents and unemployed of the mental age 10 
years differ greatly from unselected 10-year children, 
the difference may be attributed to the superior 
chronological age of the former. 

A good deal of such influence was found in certain 
of the tests. The influence, however, is not always in 
the same direction. With some tests, age tends to 
increase, with others to decrease, the percentage of 
successes. Indeed, there are more marked cases of 
negative influence than of positive. Among those 
negatively influenced are: ^^ rhymes,'^ ^'six digits,'' 
''60 words," ''20-22 syllables," "disarranged sen- 
tences," "sense of selection" and "fables"; also, 
though to a less extent, "date," 'Hhree words," "de- 
signs," "reading for memories," "26-28 syllables," 
"five digits reversed" and "similarities" (three 
things). In finding rhymes, for example, Williams' 
older delinquents and KnoUin's unemployed adults do 
no better at Mental Age 13-14 than unselected chil- 
dren of 10 years. Almost as great a difference in the 
same direction is found in the test of repeating six and 
seven digits, naming 60 words, repeating five digits 
backwards, and giving sense of selection. 

The positive influence of age, i. e., that which causes 
increase in the percentage of passes, is in evidence with 
the following tests: 'induction," "physical relations," 
"months," "vocabulary," "comprehension" (Age X), 
"making change," "problems of fact" and "enclosed 
boxes." In "comprehension" (Age X), for example, 
Knollin's adults of 10-year mental level do about as 
well as unselected children of 11 years. In the induc- 
tion test the adults of 13-year mental level are far 
superior to unselected children of 14 years, and the 



140 STANFORD REVISION OF BINET-SIMON SCALE 

difference is almost as mai'ked for most of the other 
tests listed above. 

Kulilmann's data on the infiiience of age are in 
some respects the most valuable yet offered on this 
subject.! His method was to compare older and younger 
feeble-minded children with reference to the percent- 
age that passed each individual test in the Binet 190S 
scale from Year III to Year X. Evidence of more or 
less mfluence of age was found with the following tests : 
*^ pointing to eyes, nose and mouth/' '' giving last 
name," ''repeating three digits," ''copying a square," 
"counting four pennies," "definitions by use"; "re- 
peating five digits," "naming four coins," "reading 
for two memories," "naming days of the week" and 
"naming the months." In only three of the tests, 
however, was the influence great enough to amount to 
a displacement of the test by as much as one year. 
These were "repeating 3 digits," "definitions by use" 
and "naming four coins." 

Pintner and Paterson made a similar comparison of 
feeble-minded children above and below the chrono- 
logical age of 15 years with respect to the percentage 
at each mental age that passed two tests — "days of 
the week" and "months of the year." Their results, 
which are given in Table 42, show a fairly large influence 
of age. The mental ages were determined by the 
Goddard revision. " 



^Kiihlmann: The Binet-Simon tests of intelligence in grading 
feeble-minded children. J. of Psycho. Asthenics, 16: June, 1912, pp. 
173-193. See especially pp. 182-185. 

2R. Pintner and D. G. Paterson: Experience and the Binet-Siino n 
tests. The Psychological Clinic, 8: Dec, 1914, pp. 197-200. 



VALIDITY OF THE INDIVIDUAL TESTS 



141 



TABLE 42 



Number op Feeble-Minded Above and Below 15 Years of Age that Pae 
Certain Tests. (From Pintner and Paterson) 


Tests 


Chron. 
Age 


Mental Ago 


4 


5 


6 


7 


8 


9 


No. 


Per- 
cent 


No. 


Per- 
cent 


No. 


Per- 
cent 


No. 


Per- 
cent 


No. 


Per- 
cent 


No. 


1 

c 


Days 
)f Week 

VIonth 
)f Year 


Below 15 
Above 15 

Below 15 
Above 15 


21 

28 


4.8 
14.3 


52 
50 

19 
36 


27 
54 

5.3 
13.9 


95 

77 

66 
70 


59 

80.5 

10.6 
28.6 


100 
127 

100 
112 


87 
98.5 

35 
68 


72 
128 

71 
128 


98.6 
100 

77.5 
92.3 


31 
101 

31 
101 





The following tests are also thought by Pintner and 
Paterson to be subject to age influence, although no 
data are offered in support of their belief: ^'counting 
13 pennies/' '' copying a square/' ^'diamond/' ^^nam- 
ing colors/' 'Helling forenoon from afternoon" and 
defining in terms of use." On the other hand, they 
present data which show that with the Knox Cube 
Test and Knox Feature Profile Test, younger feeble- 
minded children do better than older feeble-minded 
children of the same mental age.^ 

Chotzen, who made a similar comparison between 
the older and the younger feeble-minded children of 
each mental age, found a marked influence of age only 
in the following tests: ''writing from copy, "writing 
from dictation," "reading for two memories" and 
naming the days of the week." A slight influence of 
age was found in the case of the following; three com- 

3 Pintner and Paterson : The factor of experience in intelligence 
testing, The Psych, Clinic, 9: 1915, pp. 44r-50. 



142 STANFORD REVISION OF BINET-SIMON SCALE 

mands/^ ^^ counting backwards, and repeating 16 syl- 
lables.'^ It will be noted that those that showed marked 
influence of age are all tests which relate largely to 
matters of information, particularly school informa- 
tion. According to Chotzen's data, age, apart from 
intelUgence, plays no part in the case of tests ^Hhat 
demand abihty to judge and to combine, or with such 
as make severe demands upon comprehension, such as 
comparison, problem-questions, noting omissions, or 
repeating five digits."^ 

Wallin compared epileptics above and below 21 
years of age with respect to the following tests: time 
of naming four colors, time of reading B.-S. selection, 
memories from reading B.-S. selection, time of nam- 
ing 60 words, and time for solving the Goddard form 
board. 5 No important difference was found except 
in the case of one or two tests. Epileptics above 21 
were superior with respect to time required for reading 
the selection, but those below 21 retained more mem- 
ories. In the form-board test, the younger subjects 
were a Uttle superior to the older. Wallin concludes 
that common age standards can be used, without much 
error, for both subnormal children and subnormal 
adults. 

It is hard to summarize the foregoing studies, be- 
cause their data are not wholly comparable. The 
subjects of Wallin were epileptics and were grouped 
for comparison into those below and those above 21 
years of age. The subjects of Kuhlmann, Chotzen, 
and Pintner and Paterson were all feeble-minded, but 



^ F. Chotzen: Die Intelligenzpriifungmethode von B.-S. bei schwach- 
sinnigen I^ndern., Zeit. f. Ang. Psych., 6: 1912, pp. 411-494. See 
especially p. 453. 

° J. E. W. Wallin: The Binet-Simon tests in relation to the factors of 
experience and maturity, The Psychological Clinic, 8: Feb., 1915, 266- 
271. 



VALIDITY OF THE INDIVIDUAL TESTS 143 

were grouped differently by age. Pintner and Pater- 
son took Age 15 as the dividing line, while Kuhlmann 
made four groups, as follows: Ages 6-10, 11-15, 16-25, 
16 and over. Chotzen's figures are of limited value 
because of the small age differences among his 236 sub- 
jects, most of whom were between 8 and 10 years old. 
Our own comparison is between normal individuals 
and backward groups of the same mental age. More- 
over, only a part of the subjects of our backward groups 
(delinquents and unemployed) were actually retarded 
to any serious degree. Our data on the influence of 
age are also limited to the tests above the middle part 
of the scale. 

Conclusions 

1. The influence of the age factor on ability to pass 
the tests of the Binet scale does not appear to be great 
enough or frequent enough to affect seriously the ac- 
curacy of the scale as a whole. 

2. Tests which are significantly easier for older than 
for younger subjects of a given mental age include the 
following: ^^days of week,'' ^^ months of the year," 
'^reading a selection,'' ^^ writing from dictation," 
^'naming coins," ^'making change," ^'defining in terms 
of use," ^'induction," '' vocabulary," ^'physical rela- 
tions," '^ problems of fact" and the ''hard comprehen- 
sion" questions. 

3. Tests which are significantly harder for older 
than for younger individuals of a given mental age 
include: ''rhymes," "six digits," "60 words," "20-22 
syllables," "disarranged sentence," "sense of selec- 
tion" and "fables." 

Kuhlmann' s assumption that age never exerts a 
negative influence is certainly not valid when "age" 
is taken in the sense in which it is here employed. 



144 STANFORD REVISION OF BINET-SIMON SCALE 

However, the assumption might hold for age in the 
sense of maturity apart from experience. The fact that 
adults of a given mental age are inferior in certain 
tests to unselected school children of the same mental 
age is probably accounted for by the more recent prac- 
tice of school children in the type of operation called 
for^ by those tests. This explanation would seem to 
hold especially for such tests as '' memory for digits/^ 
''memory for sentences/^ ''three words/' " rhymes/' 
"reading for memories/' "sense of selection/' "fables/' 
etc. 

4. With regard to memory, the data are contradic- 
tory. Kuhlmann finds a positive influence of age for 
"three digits" and "five digits"; Chotzen classes 
"memory for digits" with the tests uninfluenced by 
age, while with our own subjects age has a markedly 
negative influence on memory for six and for seven 
digits. In the test of "reading for memories" our 
older subjects of a given mental age read more rapidly 
than the younger but give fewer and less literal mem- 
ories. The adult unemployed were especially inferior 
to school children of the same mental age in giving 
literal memories — a characteristic which was strikingly 
evident also in the test of giving the sense of a selec- 
tion heard. In the latter test the almost irresistible 
tendency of the older subjects was to give a critical 
reaction or comment, rather than an epitome of the 
thought contained in the selection. 

5. The data available throw little light on the influ- 
ence of maturity apart from the influence of experience 
which comes with increased age. It is not improb- 
able that the influences we mention are due less to 
maturity, as such, than to the experience incident to 
age. 



VALIDITY OF THE INDIVIDUAL TESTS 145 

6. With regard to the validity of the tests in gen- 
eral, the two most important criteria are: (a) increase 
in the percentage of unselected children that pass from 
year to year, and (b) coherency. As for the former, 
our data show that all the tests included in our revi- 
sion satisfy this criterion very well. 

7. In order to test the coherency of the scale, each 
test from V to XIV was measured against the scale as 
a whole. The results show that all the tests, including 
those which have been most criticised, are reasonably 
good tests of intelHgence, although not all are of the 
same value. 



CHAPTER VIII 

CONSIDERATIONS RELATING TO THE FOR- 
MATION OF AN INTELLIGENCE SCALE 

The Selection of New Tests 

In devising tests of intelligence it is necessary to be 
guided by certain assumptions regarding the nature of 
intelligence. To adopt any other course is to depend 
for success upon happy chance. However, it is im- 
possible to arrive at a final definition of intelligence on 
the basis of a priori considerations alone. To demand, 
as critics of the Binet method have sometimes done, 
that one who would measure intelligence should first 
ascertain exactly what intelligence is, is quite un- 
reasonable. As Stern points out, electrical currents 
were measured long before their nature was well 
understood. Similar illustrations could be drawn 
from the processes involved in chemistry, physiology 
and other sciences. In the case of intelligence it may 
be truthfully said that no adequate definition can 
possibly be framed which is not based primarily on the 
symptoms empirically brought to light by the test 
method. The best that can be done in advance of 
such data is to make tentative assumptions as to the 
possible nature of intelligence and then subject these 
assumptions to tests which will show their correctness 
or incorrectness. New hypotheses can then be framed 
for further trial, and thus gradually we shall be led 
to a conception of intelligence which will be meaning- 
ful and in harmony with all the ascertainable facts. 

146 



FORMATION OF AN INTELLIGENCE SCALE 147 

This, in fact, was the method of Binet. Only those 
unacquainted with Binet's more than fifteen years of 
labor preceding the publication of his intelligence 
scale would think of accusing him of making no effort 
to analyze the mental processes which his tests are 
designed to measure. It is true that many of Binet's 
earher assumptions proved untenable, but he was then 
always ready to acknowledge his error and to plan a 
new line of attack. The exceptional candor and 
intellectual plasticity which he displayed in his patient 
researches with intelligence tests should serve as a 
splendid example to all who would contribute to this 
difficult field of psychology. 

It is not our purpose to enter here into a criticism of 
the various tentative definitions of intelhgence. Among 
the most noteworthy of such definitions, or concep- 
tions, are those of Ebbinghaus, Binet, Meumann, 
Stem, and Spearman. These conceptions may be 
briefly characterized, in order, as follows: 

Binet's conception of intelligence emphasizes three 
characteristics of the thought process: (1) its tendency 
to take and maintain a definite direction, (2) the 
capacity to make adaptations for the purpose of at- 
taining a desired end, and (3) the power of auto- 
criticism. ^ 

According to Ebbinghaus, the essence of intelligence 
lies in comprehending together, in a unitary, meaning- 
ful whole, impressions and associations which are more 
or less independent, heterogeneous or even partly con- 
tradictory. ^'Intellectual ability consists in the elabor- 

^ See Binet and Simon: L'intelligence des imbeciles. VAnnee psychol- 
ogique, 15, 1909, pp. 1-147. The last division of this article is devoted to 
a discussion of the essential nature of the higher thought processes 
and is a wonderful example of that keen psychological analysis in which 
Binet was so gifted. This and other conceptions of inteUigence are 
reserved for treatment elsewhere. 



148 STANFORD REVISION OF BINET-SIMON SCALE 

ation of a whole into its worth and meaning by means 
of many-sided combination, correction, and comple- 
tion of numerous kindred associations. — It is an 
activity of combination.^' 

Meumann offers a two-fold definition. From the 
psychological point of view, intelligence is the power 
of independent and creative elaboration of new pro- 
ducts out of the material given by memory and the 
senses. From the teleological point of view, it in- 
volves the ability to avoid errors, to surmount diffi- 
culties, and to adjust to environment. 

Stem defines intelligence purely in teleological terms 
as 'Hhe general capacity of an individual consciously 
to adjust his thinking to new requirements: it is gen- 
eral adaptability to new problems and conditions of 
Hfe.^' 

Spearman, Hart and others of the English school 
define intelligence as a ^^ common central factor" which 
participates in all the special mental activities. This 
factor is explained in terms of a psycho-physiological 
hypothesis of '' cortex energy, '^ '' cerebral plasticity,'' 
etc. 

These conceptions are only to a slight extent con- 
tradictory or inharmonious. They differ mainly in the 
point of view from which they are framed and in the 
location of emphasis. Doubtless each expresses a 
part of the truth and no one all of it. In devising new 
tests it is well to keep in mind all of these conceptions 
and others as well. We may thus be spared much 
fruitless testing of mental processes which are little 
concerned in intelHgence. All the conceptions given 
agree in locating intelligence chiefly among the higher 
and more complex processes, as distinguished from the 
elementary and simple. Tests of sensory discrimina- 



FOEMATION OF AN INTELLIGENCE SCALE 149 

tion, reaction, time, etc., have proved themselves all 
but valueless in the measurement of intelligence. 
Seashore's suggestion that in order to avoid influences 
of training we should seek for intelligence tests among 
processes which mature so early as not to show age 
differences after the early years of childhood, finds no 
warrant in any of the published results of intelligence 
testing. 

When a test is found which from inspection appears 
capable of bringing to light individual differences in 
the mental traits involved in any reasonable concep- 
tion of intelligence, it should be tried. As we have 
already indicated, the best way to do this is to apply 
the test to a large number of unselected children of 
different ages. If the percentage of success increases 
but little or not at all with age, the test may as well 
be discarded. On the other hand, if the proportion 
of successes increases significantly with age, then the 
test is a valid measure of intelligence unless the increase 
is due to maturity or experience apart from intelligence. 
To ascertain whether intelligence, rather than maturity 
or experience, is responsible for the increase it is neces- 
sary to compare the intelligence of those children of a 
given age who pass the test with the intelligence of 
children of the same age who fail it. This comparison 
is readily made if an intelligence scale is available which 
is known to have a certain degree of validity. It is the 
method we have employed in the preceding chapter. 
When no such scale is available for comparative pur- 
poses we can still check up the validity of a test by 
utilizing school records, teachers' estimates of the 
children's intelligence, and other criteria. It is perhaps 
always best to use those criteria in addition to meas- 
uring the individual test against an existing scale. 



150 STANFORD REVISION OF BINET-SIMON SCALE 

It can not be too strongly emphasized, however, 
that a test may under ideal laboratory conditions be 
a vaUd measm-e of intelligence and yet not be usable 
under the Hmitations of time and equipment which 
usually prevail in Binet testing. To be widely service- 
able a test should demand only the simplest material 
or apparatus, should require at most but a few minutes 
of time, and should lend itself well to uniformity of 
procedure in application and scoring. 

The Assembling of Tests into a System 

The Binet scale has often been criticised as a hetero- 
geneous aggregation of tests without plan or system. 
This criticism is based on the assumption that the only 
way to measure intelligence is first to measure separ- 
ately the individual mental functions involved in 
intellectual processes and then to summate the results. 
It would thus be necessary to have separate scales for 
such functions as accuracy of perception, memory, 
logical association, reasoning, judgment, etc., or pos- 
sibly several scales for each one of these functions, in 
order to measure its efficiency with different kinds of 
material. 

From this point of view, the Binet scale is indeed a 
'^ motley array'' of tests. Although there are several 
memory tests, no effort is made thoroughly to test any 
kind of memory. There are three tests that involve 
drawing with pen or pencil, but there is no pretense of 
testing thoroughly any particular functions involved 
in drawing from copy or memory. The same may be 
said of various tests of association, mastery of lang- 
uage, comprehension, reasoning, etc. How, it is 
often asked, can the scale measure intelligence as a 
whole when it offers no reliable measure of any single 
aspect of intelligence? 



FORMATION OF AN INTELLIGENCE SCALE 151 

This is the point of view of '^faculty psychology," 
which, far from being defunct, has really given direc- 
tion to much of the current work in intelligence test- 
ing. It was the point of view which long controlled 
the work of Binet, who, like others, began by attempt- 
ing to get at intelligence by measuring memory, at- 
tention, sense discrimination and other individual 
functions. It was only after years of exploration 
along the old lines that he finally broke away from 
them and undertook, so to speak, to triangulate the 
height of the tower without first getting the dimen- 
sions of the individual stones which made it up. The 
assumption that it is easier to measure a part, or one 
aspect, of intelligence than all of it, is fallacious in 
that the parts are not separate parts and can not be 
separated by any refinement of experiment. They 
are interwoven and intertwined. Each ramifies every- 
where and appears in all other functions. The analogy 
of the stones of the tower does not really apply. Mem- 
ory, for example, cannot be tested separately from at- 
tention, or sense discrimination separately from the 
associative processes. After vainly trying to disen- 
tangle the various intellective functions Binet decided 
to test their combined functional capacity without any 
pretense of measuring the exact contribution of each 
to the total product. IntelHgence tests have been 
successful just to the extent to which they have been 
guided by this aim. 

Memory, attention, imagination, etc., are terms of 
structural psychology. Binet 's psychology is dynamic. 
He conceives intelligence as the sum total of those 
thought processes which consist in adaptation. This 
adaptation is not explicable in terms of the old mental 
faculties. No one of these ^'faculties" can explain a 



152 STANFOKD REVISION OF BINET-SIMON SCALE 

single thought process, for such process always in- 
volves the participation of many ^^ faculties/' whose 
separate roles are impossible to distinguish accurately. 
Instead of measuring the intensity of various mental 
states (psycho-physics), it is more enhghtening to 
measure their combined effect on adaptation. Using 
a biological comparison, Binet says the old ^'faculties" 
correspond to the separate tissues of an animal or 
plant, while his own ^^ scheme of thought" corres- 
ponds to the functioning organ itself. Binet' s psy- 
chology was a functional rather than a structural 
psychology. 2 

Binet's conception of ^'general intelligence," although 
expressed in psychological terms, harmonizes well with 
Spearman and Hart's psycho-physiological conception 
of intelligence as depending upon general cerebral 
efficiency, or '^ cortex energy." The assumption is 
common to both that a common factor, 'intelligence" 
(Binet) or '' general ability" (Spearman), enters into 
every specific mental performance of an individual, 
and that by testing a subject with a large variety of 
mental tasks the special factors involved are canceled 
and the general factor revealed. If Binet's theory of 
intelligence is vahd, we must reject those criticisms 
which condemn the scale for its failure to test out and 
follow up individual mental functions from childhood 
to maturity. The incorporation in the scale of hetero- 
geneous tests and the partial lack of consecutiveness 
in their arrangement were the result, not of accident, 
but of a well-defined theory. Whether the underly- 
ing theory is correct, is a matter to be determined by 
patient research. 

2 See Binet and Simon: L'intelligence des imbeciles, L'Annee Psy- 
chologique, 15, 1909. Especially pp. 143-147. 



FORMATION OF AN INTELLIGENCE SCALE 153 

It is unfortunate that off-hand criticisms of the 
Binet method have been so confidently voiced by psy- 
chologists who have evidently not taken the trouble to 
acquaint themselves with Binet^s work. One of these 
criticisms is to the effect that since the tests of suc- 
cessive years in the scale do not follow up the same 
functions, the different '^mental ages'^ are therefore 
not comparable; that we do not know, for example, 
how a child of Mental Age VIII differs from one of 
Mental Age VI, since the two mental ages have not 
been earned by tests of the same functions. The 
criticism implies that ^'mental age,'^ in terms of the 
Binet scale, is meaningless. We would urge, however, 
that whether the different mental ages have meaning 
and are comparable is a question which can only be 
settled experimentally. We have already shown 
(Chapters III and VI) that the evidence strongly sup- 
ports the validity of the Binet method. Knowing 
that a given child of 6 years has a mental age of 5 
years by the Binet scale, we are able to forecast fairly 
accurately the mental age the child will have at 12 
years, and even the probable degree of his school 
success. The proof of the Binet method is in the fact 
that it works so well. Investigation alone will de- 
termine whether a scale made up on the plan advocated 
by Rossolimo, Thorndike, Yerkes and others (that is, 
a scale designed to follow up and measure individual 
functions separately) is capable of furnishing an in- 
dex of intelligence any more reUable or any more 
meaningful for purposes of age comparison than that 
secured by the Binet scale. Indeed, it is conceivable 
that a scale whose various year-groups of tests were 
composed with studied effort to make them dissimilar 
and non-comparable might still give intelligence 



154 STANFORD REVISION OF BINET-SIMON SCALE 

quotients of high vaHdity at the different ages. It is 
to be hoped that someone will make such an experi- 
ment. 

Whatever the facts may prove to be, it is probably 
desirable for the present to include several varieties 
of tests in each year group, and as far as possible to 
avoid extreme dissimilarity in the general character of 
the tests of successive years. It may even be desir- 
able, when it is convenient, to have the same test or 
the same type of test recur at different age levels. 
Binet, himself, frequently followed this plan. It is not 
at all certain, however, that it is necessary for the pur- 
pose of measuring general intelligence to go much 
farther than did Binet in the direction of testing out 
the special mental functions. 

The Location and Scoring of Tests 

The percentage of correct responses necessary for 
locating a test is a much-debated question. Binet's 
standard was a shifting one, varying from 60 to 90 
percent according to the upward trend of the curve for 
the test in question. Goddard, Kuhlmann, Bobertag, 
Stem and Meumann adhere strictly to the 75 percent 
standard. Bobertag and Stem seek to justify this 
standard by the (supposed) fact that it gives a fairly 
normal distribution of mental ages and causes ap- 
proximately 50 percent to test "at age," that is, withid 
12 months of normal. It is true that the 75 perceDi 
standard has this effect at a certain part of the scale. 
It is evident, however, from the data presented in 
Chapter III, that the relation between the 75 percent 
standard and the 50 percent testing "at age" is a 
purely accidental one. That it should hold at any 
point is due to the chance ratio that obtains for a 



FORMATION OF AN INTELLIGENCE SCALE 155 

certain period between chronological age and the rate 
of growth. There can be no correct scale which will 
cause 50 percent of unselected children to test '^at 
age'' at all the age levels. If the scale is accurate it 
appears that the proportion of ^^at age" cases among 
4-year-olds will be about twice as great as among 8- 
year-olds and about three times as great as among 12- 
year-olds. That is, the curve of distribution of mental 
ages of unselected children becomes more and more 
flattened as we ascend to the higher age groups. 

This last statement is only another way of expressing 
the familiar fact that, relative to the mental develop- 
ment already attained, a year of growth amounts to 
less in the upper than in the lower years. A year of 
mental growth added to the mental age of 5 years 
amounts to an increase of 20 percent, while a year 
added to the mental age of 10 years is an increase of 
only 10 percent. It is evident, therefore, that if a 
scale contains a group of tests at each age level, these 
groups become progressively closer together up the 
scale, until finally, when the point of mental maturity 
has been attained, the successive age groups are not 
separated at all. The distance between the 5-year and 
6-year tests is as great as that between the 10-year and 
12-year tests, and 21-year tests are probably not 
separated from 20-year tests by any distinguishable 
distance whatever. 

This crowding up of the age levels in the upper 
years is of greatest significance as regards the per- 
centage of passes necessary for locating tests in a 
scale like the Binet, for it means that the true standard 
percentage is not uniform for the different age levels, 
but variable. This will be evident if the following 
facts are borne in mind: 



156 STANFORD REVISION OF BINET-SIMON SCALE 

1. A child does not earn a given mental age, say 8 
years, by his performances on the tests of the 8-year 
group alone. He earns it by certain successes imthe 
8-year group, plus certain successes in the succeeding 
year-groups, minus certain failures in the preceding 
year-groups. 

2. Since the year-groups above the given mental 
age are relatively closer together than the year-groups 
below that mental age, it is evident that if the tests of 
all the different age-groups are located according to the 
same standard (say 75 percent of passes), then unse- 
lected children of any given age will, on the average, 
attain more successes above their age than they will 
suffer failures below their age. 

3. In testing unselected children of the various ages 
with a scale of this kind (that is, a scale having an 
equal number of tests at each age and all tests located 
according to a uniform standard) the ratio between (a) 
the successes above a given age attained by the children of 
that age and (b) the failures below that age suffered by the 
same children can not be exactly the same at any two age- 
levels. This would cause a displacement, and an un- 
equal displacement, of median mental age from median 
chronological for the children of the upper age-levels. 

4. It must be especially borne in mind, that the 
guiding principle in the formation of an accurate scale 
is that the median mental age must coincide with median 
chronological age for unselected children of each age. 

There are three ways of overcoming these difficulties 
so as to bring it about that median mental age will 
coincide with median chronological age: (1) the num- 
ber of tests m the upper age-groups may be progres- 
sively reduced, (2) the tests of the upper age-groups 
may be located on the basis of a smaller and smaller 
percent passing; or (3) the two methods may be com- 
bined. 



FORMATION OF AN INTELLIGENCE SCALE 157 

Binet's 1911 revision meets the situation in part by 
omitting certain year-groups of tests altogether. The 
upper tests of both the 1908 and 1911 series are also 
somewhat harder for the age in which they occur than 
are the tests at the lower end of the scale, though this 
was probably unintentional. The difficulty can really 
not be satisfactorily solved by a progressive reduction 
in the number of tests, since tests can only be dropped 
by wholes. In certain cases, to retain a test would 
give too much advantage in one direction, while to 
drop it would throw too much weight in the opposite 
direction. 

In the Stanford Revision we have fewer tests per 
year in the upper part of the scale than in the lower, 
but we have not attempted to make the decrease 
perfectly gradual. Instead, whole year-groups have 
been omitted. This irregularity was then remedied 
empirically in three ways: (1) the number of tests in 
Group XII was increased to eight; (2) higher values 
were assigned to the tests of the ^^ average adult ^' and 
'^superior adult '' groups; and (3) tests were located in 
the upper groups on the basis of a smaller percent 
passing. Changes along these lines were continued 
until an arrangement was found which caused the 
median mental age of unselected children of any age 
to coincide approximately with median chronological 
age. When the tests had been arranged in such a way 
as to bring this about, it was found that they were 
passed by the following percents in the locations as- 
signed them. 3 

2 The percents from IV to XIV, inclusive, are those found for Stan- 
ford unselected cases in 1914-1915. As unselected cases were not 
available for the "average adult" and "superior adult" tests, the figures 
for those were obtained by taking the arithmetical average of the 
percents for the high-school pupils, the business men, WiUiams' de- 
linquents of the "average adult" level and KnolUn's unemployed of 
the same level. The resulting figure presmnably shows what " average 
adult" intelligence can do with the tests of the "superior adult" group. 



158 STANFORD REVISION OF BINET-SIMON SCALE 

TABLE 43 



Year 


Average Percent 


Year 


Average Percent 


Group 


Passing 


Group 


Passing 


IV 


77 


IX 


62.3 


V 


71.3 


X 


64.5 


VI 


70.8 


XII 


62.4 


VII 


68 


XIV 


55.6 


VIII 


63.2 


"Av. Adult" 


59.8 






''Sup. Adult" 


37.4 



The percents are the averages for the regular tests 
only; the alternates are omitted. The figure for XIV 
does not include the clock problem, owing to a change in 
the method of scoring employed in the revision, and 
in '^ superior adult" the test of repeating seven digits 
backward is not taken ino account for lack of suf- 
ficienct data. 

It will be noted that from IV to IX there is a general 
decrease in the average percent of passes for the tests 
of successive year-groups. This is what we should 
expect from the facts set forth. Beyond IX, however, 
the percents vary more or less irregularly, owing to 
the omission of XI, XIII, XV, etc. The omission of 
XI must also affect the placing of tests in IX and X. 
If tests were included at XI, then the tests of IX and X 
would either have to be made harder or else shifted 
downward in order to keep the median mental ages 
at these levels from running too high. 

It is evident that the percents beyond VIII have no 
applicability or meaning apart from the present scale 
as it is actually constituted. A scale constructed 
somewhat differently, with more or fewer groups of 
tests in the upper ranges, or with slightly different 
values assigned to the tests of the different year-groups, 
would require other percents for the correct location 



FORMATION OF AN INTELLIGENCE SCALE 159 

of the tests. Similarly, the percents below IX would 
lose general significance if any of the year-groups were 
omitted. As stated elsewhere, we have not been 
guided by theoretical considerations in locating the 
tests, but by the one purpose of securing an arrange- 
ment which would give median mental ages as nearly 
as possible equal to the median chronological ages. 
Although we have endeavored to keep the tests of a 
given age-group as nearly as possible of the same 
difficulty, it must always be remembered that the 
correct location of a test does not depend wholly upon 
the percent that pass it any one year. 

It would be much more satisfying if the difficulties 
of the age-grade method could be disposed of on the 
basis of purely logical considerations, without the 
necessity of trial and error. The problem is so in- 
volved, however, that such a solution is not easy. 
For example, to make a correct scale by reducing in 
exactly the right proportion the number of tests in 
the upper years, or by introducing a variable standard 
for locating the tests in the different year-groups, 
would be impossible on logical considerations unless 
we had exact knowledge as to the normal rate of 
growth at every point. 

It would doubtless be possible to construct an in- 
telligence scale by a method based purely on logical 
consideration. Mr. Otis^ has formulated such a plan 
which involves, among other features, the location of 
each test at the age where it is passed by 50 percent 
of unselected children. However, Mr. Otis' sugges- 
tions are hardly apphcable to a scale like that of Binet 
and so need not be set forth here. 



* In a thesis on "The logical and mathematical aspects of intelligence 
testing by the Binet method," Psychological Review, March and May, 
1916. 



160 STANFORD REVISION OF BINET-SIMON SCALE 

Point Scales 

Yerkes has strongly emphasized the advantages of a 
point scale as contrasted with the age-grade method 
of Binet. Three advantages are claimed for the point 
scale: (1) that it becomes better standardized, the 
more widely it is used, however much the results se- 
cured lack agreement; (2) that the point scale admits 
of more ready comparison of intelligence norms of the 
sexes, different races, and the various social classes; 
(3) that it more conveniently permits the giving of 
partial credit for partial success in a test. 

These claims are less valid than they at first appear. 
In the first place, the lack of agreement in Binet data 
is unquestionably due in large measure to lack of uni- 
formity of procedure in giving and scoring the tests, 
that is, to sources of error which are no more avoidable 
in the use of a point scale than any other. We have 
tried to remedy this defect for the Binet scale by pre- 
paring a very detailed guide. 

In the second place, it can not be admitted that the 
Binet norms necessarily become more insecure or 
''muddled^' with the accumulation of data collected 
by satisfactory procedure. Such data can, in fact, be 
readily utilized for purposes of revising the scale from 
time to time. Another way would be to let the scale 
stand, admittedly imperfect as it is, but to make use 
of all available results for correcting the intelligence 
quotients which the scale gives at each age. If it 
should be found, for example, that the present revi- 
sion gives for an indefinitely large number of unselected 
6-year-olds a median intelligence quotient of 103, 
instead of the desired 100, it would then be merely 
necessary to use 103 as the norm instead of 100. 
Similarly with an error in either direction at any other 
age. 



FORMATION OF AN INTELLIGENCE SCALE 161 

Finally, as shown in Chapter III and as is implied 
above, the Binet method becomes itself a point scale 
as soon as we express intelligence status in terms of 
the intelligence quotient. In terms of its '^ points" 
(that is, units of intelligence quotient) we may com- 
pare sexes, races or social classes as readily as by any 
other point scale. Moreover, the ^^ points" of the 
Binet scale are more nearly equal units than can pos- 
sibly be the case with a point scale whose various 
tests have had point values assigned to them in an 
arbitrary and off-hand manner. ^ 

The question whether a scale to be vaUd must give 
partial credit for partial success in a test is another 
aspect of the question whether it is necessary for the 
tests to follow up the development of individual func- 
tions. In addition to what we have already said on 
this matter it may be pointed out that it is impossible 
entirely to avoid the ^'all or none" principle in scoring. 
A subject who is being tested even by the Yerkes- 
Bridges scale will in many cases lose '^points" because 
his ability in the function tested falls just a little short 
of that necessary to earn the credit assigned to the test^ 
or part of a test. There is one real advantage, how- 
ever, in giving as far as it is convenient to do so, 
partial credit for partial success; it makes it possible 
to get along with a somewhat smaller number of tests. 
By following this method, as we have done with the 
tests of vocabulary, fables, ball and field, etc., we may 
make a single test serve as two or three, or even more 
tests. 



^ See Arthur S. Otis: A criticism of the Yerkes-Bridges point scale, 
with alternative suggestions, Journal of Educational Psychology , March, 
1917. 



162 STANFOKD REVISION OF BINET-SIMON SCALE 

Summary 

1. In the selection of intelligence tests it is neces- 
sary to be guided by a tentative conception as to the 
nature of the processes to be measured. It is unreason- 
able, however, to demand that intelligence testing 
wait upon a complete definition of intelligence. Such 
a definition can be arrived at only empirically, by the 
use of tests which bring to light the symptoms of in- 
teUigence. 

2. Many of the criticisms of the Binet method are 
based on an unfortunate lack of acquaintance with 
Binet's psychological work and of the considerations 
which shaped his system of tests. Whether the age- 
grade method is inferior to the ''profile'^ method, or 
what we might call the ''special function'' method, 
can be answered only in the light of future researches. 

3. In a system like that of Binet there is no single 
standard as to the percentage who should pass a test 
in a given year in order to determine its location in 
that year. Factors involved are: (1) the relative 
amount of mental growth from year to year, and (2) 
the nmnber and weighting of tests at the upper levels. 

4. The advantages claimed for the point-scale 
method are questionable. The most important con- 
sideration in framing such a scale, namely, that of 
equalizing the "points," has been overlooked. We 
have tried to show that the Binet scale itself, properly 
standardized, becomes automatically a point scale not 
easily improved upon. 



APPENDIX I 
The Data Utilized in the Stanford Revision 

All of the 2060 tests were made by trained examiners, with the ex- 
ception of about a fourth of the Terman-Childs cases. As explained 
in the text, the Terman, Lyman, Galbreath, Talbert, and Cuneo sub- 
jects were within two months of a birthday and were as nearly as pos- 
sible unselected. The Terman and Childs subjects were drawn from 
social classes perhaps sHghtly above the average, though this was not 
fuUy reahzed at the time the tests were made. The Terman, Trost 
and Waddle cases were tested in a trial of the Terman-Childs Tentative 
Revision of 1912. Of the 310 in the latter group, 50 were tested by 
Dr. Charles Waddle, State Normal School, Los Angeles, California, 
125 by Miss Helen Trost, a student at Stanford University, and the 
remaining 135 by Terman. They were probably of about average 
social status. Effort was made to avoid selection, but the precautions 
taken to this end were not adequate. 

The following tables give the percentage that passed each test at 
each age. Where statistics are given, it will be understood that all, 
or practically all, of the subjects of the age in question were given the 
test. A few tests, owing their improper location in the trial series, 
were not given to all the subjects to whom they should have been given, 
and in such cases the percents could not be tabulated for the desired 
range of ages. 

Terman's high-school students were from 17 to 20 years of age, were 
members of the junior and senior classes, and were all doing school 
work of about average quality. 

Dr. WiUiams' delinquents were inmates of the.Whittier State School, 
one of the three juvenile reform schools of California. It should be 
noted that the statistics for WiUiams' delinquents and KnoUin's \m- 
employed are based on the classification of these subjects by mental 
age. 

The Hopwood and Houser vocabulary tests were mass (written) 
tests of pupils from the fourth to the eighth grades in Alameda and 
Riverside, California. Approximately 30 pupUs were tested at each 
age indicated in each of these series. The Terman vocabulary data 
from college students were also collected by mass (written) tests. The 
students numbered 65 and belonged chiefly to the junior and senior 
classes. 

Since the above data were collected, additional tests have been made 
of 250 unskilled, semi-skilled, and skilled employees, 160 prisoners, 
300 additional juvenile delinquents, 130 high-school students, 80 chil- 
dren in an orphanage, 100 kindergarten children, 200 first-grade children, 
250 children in other grades, about 100 superior children, 174 children 
suspected of being feeble-minded, and 140 special-class children. Re- 
tests have also been made of nearly 150 children tested by Terman and 
Childs. The results of these investigations will be pubhshed in another 
monograph. 

163 



164 STANFORD REVISION OF BINET-SIMON SCALE 
DATA UTILIZED IN THE STANFORD REVISION 















Num 


ber at Each Age 










Source of Data 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


16 


Total 


Terman, 

Lyman, 

Galbreath, 

Talbert, 

Cuneo. 

Terman and 
ChUds. 

Terman, 
Trost, and 
Waddle. 


10 


17 
29 

5 


54 

83 

10 


117 
26 

22 


92 
29 

39 


100 

43 

44 


113 

49 

34 


87 
33 

55 


79 

44 

36 


83 98 
3517 

2522 


82 
6 

18 


46 
2 

10 


14 
7 


992 
396 

310 


Tennan's high- 
school pupils. 

Knollin's business 
men. 

Knollin's unem- 
ployed men. 

Williams' juvenile 
delinquents. 


(Ages 16-21. Junior and senior classes.) 

(Ages 25-65 years. Had not attended the 
high school.) 

("Hoboes," ages 21-60.) 

(Ages mostly 14-21.) 


32 

30 

150 

150 






2060 



Percents That Passed Individual Tests in Different Stanford 

Investigations 

(Figures at top of each column refer to ages) 

nil Parts of the Body 

3 4 5 6 

Terman, Lyman, Ordahl, etc. 80 86 100 100 (Nose, eyes, mouth, hair, 3 of 4) 

Terman and Childs 89 96 100 (Nose, eyes, mouth, 3 of 3) 

Terman, Trost, Waddle. ... 100 100 100 (Nose, eyes, mouth, 3 of 3) 



APPENDICES 165 

IIP Naming Familiar Objects 

3 4 5 6 

Terman, Ljman, Ordahl, etc. 90 100 100 100 (Key, penny, knife, watch, pen- 
cil, 4 of 4) 

Terman and Childs 93 100 100 (Key, penny, knife, 3 of 3) 

Terman, Trost, Waddle 100 100 100 (Key, penny, knife, 3 of 3) 

IIP Pictures, Enumeration 

3 4 5 6 

Terman, Lyman, Ordahl, etc. 80 94 100 100 

Terman and Childs 96 100 100 

Terman, Trost, Waddle 100 100 100 

III^ Giving Sex 

3 4 5 6 

Terman, Lyman, Ordahl, etc. 80 94 100 100 

Terman and Childs 100 100 100 

Terman, Trost, Waddle 100 100 100 100 

III^ Giving Family Name 

3 4 5 6 

Terman, Lyman, Ordahl, etc. 80 94 100 100 

Terman and Childs 95 100 100 

Terman, Trost, Waddle 75 100 100 

III^ Repeating 6-7 Syllables 
3 4 5 6 
Terman, Lyman, Ordahl, etc. 70 94 100 100 

III Alternative. Three Digits 
3 4 5 6 
Terman, Lyman. Ordahl, etc. 70 87 100 100 

Terman and ChMs 97 100 100 

Terman, Trost, Waddle 100 75 100 100 

IV^ Comparison of Lines 

3 4 5 6 

T., L., O., etc 60 85 97 99 

T. and C 100 100 100 

IV* Discriminations of Forms 
3 4 5 6 
T., L., O., etc 10 70 83 95 

IV^ Counting Four Pennies 

3 4 5 6 

T., L., O., etc 20 77 93 98 

T. andC 91 90 100 

T., T., W 80 100 100 



166 STANFORD REVISION OF BINET-SIMON SCALE 

IV* Copying Square 
3 4 5 6 

T., L., O., etc 10 71 76 95 (Pencil, 1 of 3) 

T. and C 86 91 95 (Pencil, 1 trial only) 

T., T., W 60 88 100 (Pencil, 1 trial only) 

IV^ Comprehension, 1st Degree 

3 4 5 6 
T., L., 0., etc 40 82 93 96 

rV« Repeating Four Digits 

3 4 5 6 
T., L., 0., etc 40 76 83 91 

IV Alternative. 12-13 Syllables 

3 4 5 6 

T., L., 0., etc 30 83 85 91 (12-13 syUables, 1 of 3) 

T. and C 51 83 85 (14 syUables, 1 of 1) 

T., T., W 60 75 91 (12-14 syUables, 1 of ^3) 

VI Comparison of Weights 

4 5 6 7 

T., L., 0., etc 50 70 94 96 (3-15 grams, 2 of 3) 

T. and C 97 98 95 100 (3-12, 6-15 grams. t'Both cor- 
rect, but 2nd trial aUowed) 
T., T., W 60 88 100 100 (3-12. 6-15 grams, 2 of 3) 

V^ Naming Four Colors 

4 5 6 7 

T., L., O., etc 59 74 86 97 

T. andC 65 74 84 96 

T., T., W 50 88 95 97 

V^ Aesthetic Comparison 

4 5 6 7 

T., L., O., etc 64 73 94 96 

T. andC 80 88 83 90 

T., T., W 60 86 90 98 

V* Definitions — Use or Better 
4 5 6 7 

T., L., O., etc 51 69 92 98 (BaU, fork, table, chair, horse, 

pencU, 4 of 6) 

T. and C 86 91 83 90 (Fork, table, chair, horse, 

mamma, 3 of 5) 

T., T., W 60 100 100 100 (Like Terman and Childs) 



APPENDICES 167 

V^ Patience, or Divided Rectangle 
4 5 6 7 

T., L., O., etc 21 70 92 95 (2 of 3. 1 minute each) 

T. andC 70 88 95 100 (2 of 3. No time limit) 

T., T., W 50 75 90 (2 of 3. 1 minute each) 

V^ Three Commissions 
3 4 5 6 7 

T., L., O., etc 20 50 72 91 93 (Order must be correct) 

T. and C 72 81 87 95 (Correct order not required) 

T., T., W 50 80 94 95 (Correct order) 

V Alternative. Giving Age 

3 4 5 6 7 

T., L., O., etc 50 76 92 98 

T. andC 72 79 96 95 

VII Right and Left 

4 5 6 7 8 

T., L., O., etc 40 50 71 86 95 (3 of 3, or 5 of 6) 

T. and C 41 73 75 90 93 (Like Bmet) 

T., T., and W 25 63 62 72 90 (Like Bmet) 

VI2 Mutilated Pictures 
4 5 6 7 8 

T., L., O., etc 27 50 65 87 96 

T. andC 34 48 57 68 82 

T., T., andW 12 33 74 86 97 

VI' Counting Thirteen Pennies 
4 5 6 7 8 

T., L., O., etc 30 46 76 93 96 

T. andC 55 74 100 100 

T., T., andW 25 67 92 94 

VP Comprehension, 2nd Degree 
4 5 6 7 8 
T., L., O., etc 25 55 70 86 93 

VI^ Naming Four Coins 
4 5 6 7 8 

T., L., O., etc 25 47 74 91 95 

T. and C 19 41 69 93 100* 

T., T., andW 25 81 95 98 

* Re-scored by new standard. Figures in original article allowed no error, 



168 STANFORD REVISION OF BINET-SIMON SCALE 

VI^ Repeating 16-18 Syllables 

4 5 6 7 8 

T., L., 0., etc 34 56 69 90 95 (1 of 3 correct, or 2 with 1 error 

each) 

T. andC 31 53 62 80 (1 of 3 without error) 

T., T., and W 38 67 77 86 (1 of 3 without error) 

VI Alternative. Forenoon and Afternoon 

4 5 6 7 

T., L., O., etc 46 60 82 97 

T. andC 65 84 87 100 

T., T., andW 51 68 88 95 

VII^ Number of Fingers 

5 6 7 8 9 

T., L., 0., etc 24 51 72 86 95 

T. andC 33 73 92 97 100 

T., T., andW 25 57 80 88 98 

VIP Pictures — Descriptions 
5 6 7 8 9 

T.,L.,0.,etc 27 56 63 88 97 

T and C 42 47 60 70 83 (Re-scored since 1912) 

T., T., andW 23 66 77 95 100 

VII^ Repeating Five Digits 

5 6 7 8 9 

T., L., C, etc 34 59 74 83 93 

T. andC 50 50 72 74 83 

T., T., andW 26 43 74 80 88 

VII^ Tying Bow-knot 

5 6 7 8 9 

T., L., 0., etc 11 35 69 88 94 

T. and C 27 61 74 (160 school children, ages 6, 7, 8) 

VII^ Giving Differences 
5 6 7 8 9 

T., L., 0., etc 23 54 66 78 90 

T. and C 19 47 62 74 85 (Re-scored since 1912) 

T., T., andW 30 61 74 86 91 

VII® Copying Diamond 
5 6 7 8 9 

T., L., 0., etc 4 30 64 83 94 (Pen, 2 of 5) 

T and C 16 42 67 90 98 (Pencil,^! trial. Re-scored since 

1912) ; 

T., T., and W 10 48 70 82 91 (PencH, 1 trial) 



APPENDICES 169 

VII Alternative 1. Days of Week 

5 6 7 8 9 

T., L., O., etc 27 65 81 91 (No error. 2 of 3 "checks") 

T. and C 56 85 85 98 (1 error aUowed. No "checks' 

used) 

VII Alternative 2. Thr ee Digits Backwards 
5 6 7 8 9 10 
T., L., O., etc 2 35 60 83 90 96 

VIII* Ball and Field (Inferior Plan) 

6 7 8 9 10 11 12 13 14 

T., L., O., etc 37 52 60 67 73 77 82 87 90 

VIII2 Counting 20-0 

6 7 8 9 10 

T., L., O., etc 16 48 66 81 96 \ 

T. andC 7 62 69 95 100 

T., T., andW 19 38 57 82 97 

VIII3 Comprehension, Third Degree 

6 7 8 9 10 

T., L., O., etc 47 59 72 85 92 

T. andC 38 57 69 78 85 

T., T., andW 20 51 62 72 81 

VHP Giving Similarities 
6 7 8 9 10 11 
T., L., O., etc 30 51 63 78 90 92 

VIII 5 Definitions Superior to Use 
7 8 9 10 

T., L., O., etc 43 62 71 83 (Balloon, tiger, football, soldier 

2 of 4) 

T. and C 34 58 77 89 (Fork, spoon, chair, horse 

mamma. 2 of 4. Re-score( 
since 1912) 

VIII ^ Vocabulary, 20 Definitions 

6 7 8 9 10 11 

T., L., O., etc 12 56 78 97 

T. andC 14 61 69 91 

T., T., andW 20 24 57 86 88 

Hopwood* 84 90 96 

Houser* 63 80 93 98 

* The tests made by Miss Margaret Hopwood and J. D. Houser, graduat 
students at Stanford University, were mass tests (written) on unselected chi! 
dren in the grades. 25 to 35 were tested at each age indicated. 



170 STANFORD REVISION OF BINET-SIMON SCALE 

VIII Alteenative 1. Naming 6 Coins 

6 7 8 9 10 

T., L., 0., etc 27 40 64 88 95 

T. and C 33 60 81 90 (Re-scored since 1912) 

VIII Alternative 2. Writing from Dictation 

6 7 8 9 10 

T., L., 0., etc 12 53 88 96 100 (Time limit, 1 minute) 

T. and C 7 79 83 100 100 (No time limit) 

IX^ Giving Date 

7 8 9 10 11 12 

T., L., O., etc 20 50 67 83 91 

T. andC 25 52 81 77 87 93 

T., T., and W 14 48 71 86 94 

Knollin's unemploj^ed. . . 65 80 98 (By mental age) 

1X2 Arranging Weights 

7 8 9 10 11 12 

T., L., O., etc 7 35 58 69 75 79 (2 of 3 trials correct) 

T. and C 25 29 55 54 77 (Only 1 trial given) 

T., T., and W 50 71 73 82 (2 of 3 trials correct) 

Williams' delinquents. . . 77 86 93 (By mental age) 

Knollin's imemployed. . . 70 79 (By mental age) 

IX' Making Change 

7 8 9 10 11 12 

T., L., 0., etc 3 38 60 83 92 (10-6, 15-12, 25-4, 2 of ^3) 

T. andC 7 26 42 55 67 (25-9. One trial) 

T., T., and W 29 62 78 91 (25-4. One trial) 

W's delinquents (By mental age) 85 100 98 

K's unemployed (By mental age) 95 98 100 (Note influence of age) 

IX^ Repeating Four Digits Backwards 

7 8 9 10 11 12 

T., L., O., etc 18 44 62 75 86 91 

W's delinquents 46 61 73 82 (By mental age) 

IX^ Three Words 

8 9 10 11 12 13 

T., L., 0., etc 44 68 81 90 95 94 

T. andC 42 60 84 86 93 

T., T., andW 48 68 86 91 90 90 

W's delinquents 95 100 100 (By mental age) 

K's unemployed 30 67 75 96 (By mental age) 



APPENDICES 



171 



IX s Finding Rhymes 
8 9 10 11 12 13 14 

T., L., O., etc 48 62 81 83 94 

T. andC 74 92 81 82 89 

W's delinquents (By 

.. mental age) 60 66 80 85 92 

K's unemployed (By men- 
tal age) 23*28 73 81 90 

, * Note poor record of adults in this test. 

IX Alternative 1. Naming the Months 

8 9 10 11 12 13 14 

T., L., 0., etc 30 59 78 90 93 96 (2 of 3 checks correct] 

T. and C. 64 91 81 96 (No check given) 

W's delinquents (Mental 

age) 78 87 88 95 (2 of 3 checks) 

K's unemployed (Mental 

age) 88 94 100 100 

IX Alternative 2. Stamps 

7 8 9 10 11 12 

T., L., O., etc 13 39 69 90 96 97 

T. andC 58 60 73 85 90 100 

T., T., andW 26 50 59 84 91 100 

XI Vocabulary, 30 Definitions 

8 9 10 11 12 13 

T., L., O., etc 25 71 80 100 100 

T. andC 14 35 60 72 77 90 

T., T., andW ....11 23 56 73 88 95 

Hopwood 65 82 90 93 (Mass tests, written) 

Houser 61 79 86 90 (Mass tests, written) 

W's delinquents 100 100 100 (By mental age) 

K's unemployed 100 100 100 (By mental age) 

Terman's high-school pupils, all passed 
j,K's business men, all passed 

X2 Absurdities 

8 9 10 11 12 13 

., L., O., etc 16 47 64 67 75 85 

T. andC 30 40 52 55 73 88 

T., T., and W 29 50 71 80 85 88 

W's delinquents 68 79 100 84 (By mental age) 

K's unemployed 50 60 82 81 (By mental age) 

High-school pupils, all passed 

X^ Drawing Designs 
8 9 10 11 12 13 14 

T., L., O., etc 27 46 60 72 81 

T., T., and W 36 50 61 72 90 

W's delinquents 67 75 88 96 88 (By mental age) 

K's unemployed 41 52 67 70 73 (By mental age) * 

* Note inferiority of adults as compared with school children of same mental 
age. 



172 STANFORD REVISION OF BINET-SIMON SCALE 



X^ Reading for 8 Memories 

8 9 10 11 12 13 

T., L., O., etc 26 55 69 80 93 

T. andC 13 46 58 65 62 (Re-scored for 8 memories 

T., T., andW 30 50 64 74 79 

W's delinquents 62 75 88 (By mental age) 

X^ Comprehension, 4th Degree 

9 10 11 12 13 14 

T., L., O., etc 44 60 74 83 88 91 

T. andC 37 59 70 80 86 

T., T., andW 45 62 65 78 90 

W's delinquents 52 70 86 97 100 (By mental age) 

K's unemployed 70 85 98 100 100 (By mental age) 

X6 Naming 60 Words 

8 9 10 11 12 13 14 

T., L., 0., etc 21 50 63 76 85 (60 in 3 minutes) 

T. andC 35 57 67 83 82 (50 required in 2 mm 

utes) 

T., T., and W 32 51 62 69 90 (50 in 2 minutes) 

W's delinquents (Mental 

age) 30 65 75 86 (60 in 3 minutes) 

K's unemployed (Mental age) 40 60 56 60 (60 in 3 minutes*) 

X Alternative 1. Six Digits 
8 9 10 11 12 13 14 

T., L., O., etc 32 56 71 80 87 

W's delinquents 46 68 73 81 86 (By mental age) 

K's unemployed 54 70 71 98 100 (By mental age) 

X Alternative 2. 20-22 Syllables 

8 9 10 11 12 13 14 15 16 

T., L., 0., etc 35 52 63 76 82 

W's delinquents 45 58 55 82 86 95 (By mentf 

age) 
K's unemployed 40 53 74 85 100 92 (By ment; 

age) 

X Alternative 3. Healy-Fernald Construction Puzzle 

8 9 10 11 12 13 

T., L., O., etc 31 46 67 81 90 

W's delinquents 75 88 92 (By mental age) 

K's unemployed 80 86 98 (By mental age) 

* Note great inferiority of adult subjects, by mental age. These did m 
seem to enter into the spirit of the test as children do. 



APPENDICES 



173 



XIII Vocabulary, 40 Definitions 

9 10 11 12 13 14 

., O., etc 2 14 58 65 78 81 

. ..ivxxdC 6 15 44 57 62 

It., T., andW 7 19 35 60 79 

f Hopwood 20 46 65 80 (Mass tests) 

Houser 4 16 41 58 70 (Mass tests) 

- delinquents 10 35 62 78 (By mental age) 

.memployed. ... 20 55 66 93 100 (By mental age) 

1 L' '(igh-school pupils. AU passed. 
, Iv : business men. AU passed. 

T's college students. All passed. (Mass tests of 65) 

XII2 Abstract Words 

10 11 12 13 14 

T., L., O., etc 27 48 57 63 72 

T. and C 20 38 51 65 67 (Binet's words. Re-scored since 

I 1912) 

W's delinquents 39 37 75 77 (By mental age) 

; K's imemployed 50 90 83 97 (By mental age) 

T's high-school pupils (91 percent of all passed) 

K's business men (90 percent of aU passed) 

XII' Ball and Field (Superior Plan) 

8 9 10 11 12 13 14 15 16 

Combined Stanford 

data for 908 cases 17 25 38 52 60 67 72 

W'B delinquents 54 65 81 78 86 84 81 (Mental age) 

K's imemployed 51 58 60 66 74 90 85 (Mental age) 

1 T's high-school pupils. . . (80 percent passed) 

I K's business men. (83 percent passed) 

XIP Dissected Sentences 
10 11 12 13 14 

, T., L., O., etc 25 49 62 71 82 

T. andC 24 32 62 66 83 

! T., T., and W 37 50 57 76 80 

1 W's delinquents 21 55 66 77 (By mental age) 

K'i? unemployed 27 54 63 (By mental age) 

' T'e iiigh-school pupils. (95 percent passed) 

K'a business men. (85 percent passed) 

XII^ Interpretation of Fables, Score 4 
10 11 12 13 14 15 16 

T. L., O., etc 37 53 62 70 81 

ndC 44 58 67 70 82 (Re-scored since 1912) 

delinquents 30 53 64 68 83 100 (By mental age) 

unemployed 20 28 52 60 73 94 (By mental age) 

t o jigh-school pupils. (90 percent passed) 
I K'e business men. (83 percent passed) 



174 STANFORD REVISION OF BINET-SIMON SCALE 

XII ^ Five Digits Backwards 
10 11 12 13 14 15 16 

T., L., O., etc 40 61 66 71 73 

W's delinquents 30 45 56 68 80 95 (By mental age) 

K's unemployed 33 48 55 60 67 78* (By mental age) 

T's high-school pupils (75 percent passed) 

K's business men. (79 percent passed) 

* Note inferiority of older subjects as compared with children of same mental 
age. 

XII' Pictures, Interpretation 
10 11 12 13 14 15 

T.,L.,0.,etc 42 50 63 74 80 

T., T., and W 30 47 65 78 84 

W's delinquents 35 46 54 62 71 (By mental age) 

K's unemployed 50 67 71 87 82 (By mental age) 

T's high-school pupils. (95 percent passed) 
K's business men. (93 percent passed) 

XII^ Finding Similarities, Three Things 
10 11 12 13 14 15 16 

T., L., O., etc 43 57 64 73 78 

W's delinquents 44 60 84 91 96 (By mental age) 

K's unemployed 50 52 56 63 73 75 (By mental age) 

T's high-school pupils. (95 percent passed) 
K's business men. (76 percent passed) 

XIV^ Vocabulary, 50 Definitions 

10 11 12 13 14 15 16 

T., L., O., etc 20 45 66 

T. andC 4 18 25 42 50 

T., T., andW 3 17 23 35 

Hopwood 6 32 40 67 (Mass tests) 

Houser 10 24 51 60 (Mass tests) 

W's dehnquents 5 10 40 58 70 90 (By mental age) 

K's unemployed 10 35 46 73 80 90 100 (By mental age)* 

T's high-school pupils. (All passed) 

K's business men. (AU passed) 

T's college students. (All passed) 

* Note superiority of adults as compared with children of the same mental age, 

XIV^ Induction Test; Finding a Rule 

11 12 13 14 15 16 

T., L., O., etc 17 38 47 56 

W's dehnquents 14 45 72 79 86 85 (By mental age) 

K's unemployed 39 44 71 80 100 100 (By mental age) 

T's high-school pupils. (78 percent passed) 
K's business men. (90 percent passed) 



APPENDICES 



175 



XIV^ President and King 

11 12 13 14 15 16 

T., L., O., etc 10 22 39 52 

T., T., and W 18 34 44 55 

W's delinquents. . / 13 20 34 59 68 76 (By mental age) 

K's unemployed. ... 20 28 46 67 64 87 (By mental age) 

T's high-school pupils. (88 percent passed) 

K's business men. (80 percent passed) 

XIV^ Problems op Fact 
11 12 13 14 15 16 

T., L., O., etc 31 39 49 56 

T. andC 40 41 48 100 

T., T., andW 38 50 61 70 

W's delinquents 21 36 53 64 77 86 (By mental age) 

K's unemployed 40 70 82 85 92 94 (By mental age) 

T's high-school pupils. (90 per cent passed) 
K's business men. (100 percent passed) 

XIV 5 Arithmetical Reasoning 

11 12 13 14 15 16 

T., L., O., etc 26 38 43 50 

T., T., and W 10 30 41 49 

W's dehnquents 22 34 45 62 86 (By mental age) 

K's unemployed 10 28 48 73 82 87 (By mental age) 

T's high-school pupils. (81 percent passed) 

K's business men. (79 percent passed) 

XIV ^ Reversing Hands op Clock 
11 12 13 14 15 

T., L., O., etc 30 54 64 78 

T., T., and W 20 59 77 89 

W's dehnquents 17 48 75 81 86 (By mental age) 

K's unemployed 10 50 63 83 91 (By mental age) 

T's high-school pupils. (90 percent passed) 

K's business men. (86 percent passed) 

XIV Alternate. Repeating Seven Digits 

11 12 13 14 15 16 

T., L., O., etc 36 41 52 59 (1 of 2 correct) 

T. and C 43 48 57 60 (Re-scored for 1 of 2 correct) 

T., T., and W 37 46 56 65 

W's dehnquents 27 30 36 52 63 78 (By mental age) 

K's unemployed 10 22 44 50 65 82 (By mental age) * 

T's high-school pupils. (60 percent passed) 
K's business men. (61 percent passed) 

* Note inferiority of adults as compared with children of same mental age. 



176 STANFORD REVISION OF BINET-SIMON SCALE 



Average Adult 1, Vocabulary, 65 Definitions 
12 13 14 15 16 

T., L., 0., etc 12 23 

T. andC 4 9 22 

T., T., andW 8 14 

Hopwood 6 13 (Mass tests) 

Houser 3 9 28 (Mass tests) 

W's delinquents 4 32 62 (By mental age) 

K's unemployed 11 24 53 77 (By mental age) 

T's high-school pupils. (84 percent passed) 
K's business men. (75 percent passed) 

T's college students. (96 percent passed) 

Average Adult 2. Interpretation of Fable, Score 8 
12 13 14 15 16 

T., L., O., etc 12 23 31 

T. andC 16 27 36 

W's delinquents 12 40 47 60 (By mental age) 

K's unemployed 6 8 20 39 65 (By mental age) 

T's high-school pupils. (66 percent passed) 
K's business men. (60 percent passed) 

Average Adult 3. Differences Between Abstract Words 

11 12 13 14 15 16 

T., L., 0., etc 11 26 39 

T. andC 16 24 29 44 

W's deUnquents 4 12 18 46 60 (By mental age) 

K's unemployed 25 43 55 76 (By mental age)* 

T's high-school pupils. (53 percent passed) 
K's business men. (66 percent passed) 

* Note inferiority of adults as compared with normal children of same mental 
age. 

Average Adult 4. Problem of Enclosed Boxes 

12 13 14 15 16 

T., L., 0., etc 8 12 22 

W's dehnquents 24 30 38 52 70 (By mental age) 

K's unemployed 10 13 40 38 70 (By mental age) 

T's high-school pupils. (55 percent passed) 
K's business men. (65 percent passed) 

Average Adult 5. Repeating of Sex Digits Backwards 
12 13 14 15 16 17 

T., L., O., etc 10 32 45 

W's delinquents 4 17 30 50 70 (By mental age) 

K's unemployed 6 14 24 30 57 69 (By mental age) 

T's high-school pupils. (56 percent passed) 

K's business men. (60 percent passed) 



APPENDICES 177 

Average Adult 6. Learning a Code 

12 13 14 15 16 17 

T., L., O., etc 8 17 32 

T., T., andW 10 19 26 

W's delinquents 10 20 50 62 70 (By mental age) 

K's unemployed 19 73 (By mental age) 

T's Mgh-school pupils. (60 percent passed) 
K's business men. (42 percent passed) 

Average Adult. Alternative 1. 28 Syllables 

11 12 13 14 15 16 

T., L., O., etc 10 26 35 39 

T. andC 21 33 42 50 

T., T., andW 15 37 40 48 

W's delinquents 8 14 24 35 46 58 (By mental age) 

K's unemployed 12 20 31 42 57 (By mental age) 

T's high-school pupils. (44 percent passed) 
K's business men. (59 percent passed) 

Average Adult 2. Comprehension of Physical Relations 

12 13 14 15 16 
T., L., O., etc 5 19 33 

W's dehnquents 31 38 46 53 60 (By mental age) 

K's unemployed 10 22 59 46 74 (By mental age)* 

T's high-school pupils. (65 percent passed) 

K's business men. (80 percent passed) 

* Note superiority of older subjects as compared with children of same mental 



Superior Adult 1. Vocabulary, 75 Definitions 
15 16 17 18 

W's dehnquents 5 10 40 (By mental age) 

K's unemployed 5 38 60 (By mental age) 

T's high-school pupils. (61 percent passed) 
K's business men. (50 percent passed) 

T's college students. (85 percent passed) 

Superior Adult 2. Binet's Paper-Cutting Test 
12 13 14 15 16 17 18 

T., L., 2 13 25 

K's unemployed 11 27 38 54 61 (By mental age) 

T's high-school pupils. (30 percent passed) 
K's business men. (43 percent passed) 

Superior Adult 3. Repeating Eight Digits 
12 13 14 15 16 17 18 

K's unemployed 6 9 11 27 34 53 62 (By mental age) 

T's high-school pupils. (37 percent passed) 
K's business men. (44 percent passed) 



178 STANFOED REVISION OF BINET-SIMON SCALE 

Superior Adult 4. Sense of Relation 

12 13 14 15 16 17 

T., L., O., etc 13 27 30 

W's delinquents 16 20 24 (By mental age) 

K's unemployed 9 18 25 38 50 (By mental age) 

T's high-school pupils. (65 percent passed) 

K's business men. (26 percent passed) 

Superior Adult 5. Seven Digits Backwards 

T's high-school pupils. (40 percent passed) 

T's 14-yr.-olds in 8th grade. (13 percent passed) 

Superior Adult 6. Ingenuity Test 

13 14 15 16 17 18 

T., L., C, etc 6 11 

W's dehnquents 8 6 30 43 (By mental age) 

K's unemployed 14 16 29 47 57 (By mental age) 

T's high-school pupils. (25 percent passed) 

K's business men. (36 percent passed) 



APPENDICES 179 

APPENDIX II 

Form Used for Gathering Supplementary Information 
To the Teacher 

The information rendered on this blank will be held strictly confi- 
dential, will be used for statistical purposes only, and without the men- 
tion of any child's name. The information will aid greatly in connec- 
tion with a revision of the Binet mental tests. 

Even if the child's social status is not accurately known, please 
underscore the word which you think would properly represent it, and 
if the uncertainty is very great, add a question mark. 

"Additional information," as caUed for in the last item, will be 
especially welcome. 

1. Name of pupil Age 

2. Name of school 

3. Present grade (Grade attended March, 1914, was ) 

4. QuaHty of child's school work (imderscore appropriate word) : 

Very inferior, inferior, average, superior, very superior. 

5. Teacher's estimate of child's inteUigence as compared with average 

children of the same age (underscore): 

Very inferior, inferior, average, superior, very superior. 

6. Social class to which the child belongs (this refers to the intellectual 

level, the culture and the general level of the home environment) : 
Very inferior, inferior, average, superior, very superior. 

7. Additional information which wiU throw light on the child's in- 

telligence, school success or social status. 















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